diff --git a/Dockerfile b/Dockerfile
index 8a970e39..fa7cb87a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,6 +9,8 @@ RUN \
     apt-get update -y && \
       DEBIAN_FRONTEND=noninteractive apt-get install -y \
       autoconf \
+      gcc-5 \
+      g++-5 \
       bash \
       build-essential \
       ca-certificates \
@@ -50,6 +52,7 @@ WORKDIR /peerplays-core
 # Compile Peerplays
 RUN \
     BOOST_ROOT=$HOME/boost_1_67_0 && \
+    export CC=gcc-5 ; export CXX=g++-5\
     git submodule update --init --recursive && \
     mkdir build && \
     mkdir build/release && \
diff --git a/libraries/app/database_api.cpp b/libraries/app/database_api.cpp
index abdc0269..0a69aba6 100644
--- a/libraries/app/database_api.cpp
+++ b/libraries/app/database_api.cpp
@@ -2148,6 +2148,8 @@ graphene::app::gpos_info database_api_impl::get_gpos_info(const account_id_type
 {
    gpos_info result;
    result.vesting_factor = _db.calculate_vesting_factor(account(_db));
+   result.current_subperiod = _db.get_gpos_current_subperiod();
+   result.last_voted_time = account(_db).statistics(_db).last_vote_time;
 
    const auto& dividend_data = asset_id_type()(_db).dividend_data(_db);
    const account_object& dividend_distribution_account = dividend_data.dividend_distribution_account(_db);
diff --git a/libraries/app/include/graphene/app/database_api.hpp b/libraries/app/include/graphene/app/database_api.hpp
index b455546d..a45e617e 100644
--- a/libraries/app/include/graphene/app/database_api.hpp
+++ b/libraries/app/include/graphene/app/database_api.hpp
@@ -118,6 +118,8 @@ struct gpos_info {
    double vesting_factor;
    asset award;
    share_type total_amount;
+   uint32_t current_subperiod;
+   fc::time_point_sec last_voted_time;   
 };
 
 /**
@@ -700,7 +702,7 @@ FC_REFLECT( graphene::app::order_book, (base)(quote)(bids)(asks) );
 FC_REFLECT( graphene::app::market_ticker, (base)(quote)(latest)(lowest_ask)(highest_bid)(percent_change)(base_volume)(quote_volume) );
 FC_REFLECT( graphene::app::market_volume, (base)(quote)(base_volume)(quote_volume) );
 FC_REFLECT( graphene::app::market_trade, (date)(price)(amount)(value) );
-FC_REFLECT( graphene::app::gpos_info, (vesting_factor)(award)(total_amount) );
+FC_REFLECT( graphene::app::gpos_info, (vesting_factor)(award)(total_amount)(current_subperiod)(last_voted_time) );
 
 
 FC_API(graphene::app::database_api,
diff --git a/libraries/chain/account_evaluator.cpp b/libraries/chain/account_evaluator.cpp
index 2d117f52..96429304 100644
--- a/libraries/chain/account_evaluator.cpp
+++ b/libraries/chain/account_evaluator.cpp
@@ -284,8 +284,10 @@ void_result account_update_evaluator::do_apply( const account_update_operation&
    {
       d.modify( acnt->statistics( d ), [&]( account_statistics_object& aso )
       {
+         fc::optional< bool > flag = o.extensions.value.update_last_voting_time;
          if((o.new_options->votes != acnt->options.votes ||
-             o.new_options->voting_account != acnt->options.voting_account))
+             o.new_options->voting_account != acnt->options.voting_account) ||
+             (flag.valid() && *flag))
             aso.last_vote_time = d.head_block_time();
       } );
    }
diff --git a/libraries/chain/db_maint.cpp b/libraries/chain/db_maint.cpp
index 931f6c63..f733bf92 100644
--- a/libraries/chain/db_maint.cpp
+++ b/libraries/chain/db_maint.cpp
@@ -749,13 +749,10 @@ void deprecate_annual_members( database& db )
    return;
 }
 
-double database::calculate_vesting_factor(const account_object& stake_account)
+uint32_t database::get_gpos_current_subperiod()
 {
-   // get last time voted form stats
-   const auto &stats = stake_account.statistics(*this);
-   fc::time_point_sec last_date_voted = stats.last_vote_time;
+   fc::time_point_sec last_date_voted;
 
-   // get global data related to gpos
    const auto &gpo = this->get_global_properties();
    const auto vesting_period = gpo.parameters.gpos_period();
    const auto vesting_subperiod = gpo.parameters.gpos_subperiod();
@@ -765,7 +762,6 @@ double database::calculate_vesting_factor(const account_object& stake_account)
    const fc::time_point_sec period_end = period_start + vesting_period;
    const auto number_of_subperiods = vesting_period / vesting_subperiod;
    const auto now = this->head_block_time();
-   double vesting_factor;
    auto seconds_since_period_start = now.sec_since_epoch() - period_start.sec_since_epoch();
 
    FC_ASSERT(period_start <= now && now <= period_end);
@@ -781,7 +777,43 @@ double database::calculate_vesting_factor(const account_object& stake_account)
          current_subperiod = period;
    });
 
+   return current_subperiod;
+}
+
+double database::calculate_vesting_factor(const account_object& stake_account)
+{
+   fc::time_point_sec last_date_voted;
+   // get last time voted form account stats
+   // check last_vote_time of proxy voting account if proxy is set
+   if (stake_account.options.voting_account == GRAPHENE_PROXY_TO_SELF_ACCOUNT)
+      last_date_voted = stake_account.statistics(*this).last_vote_time;
+   else
+      last_date_voted = stake_account.options.voting_account(*this).statistics(*this).last_vote_time;
+
+   // get global data related to gpos
+   const auto &gpo = this->get_global_properties();
+   const auto vesting_period = gpo.parameters.gpos_period();
+   const auto vesting_subperiod = gpo.parameters.gpos_subperiod();
+   const auto period_start = fc::time_point_sec(gpo.parameters.gpos_period_start());
+
+   //  variables needed
+   const auto number_of_subperiods = vesting_period / vesting_subperiod;
+   double vesting_factor;
+  
+    // get in what sub period we are
+   uint32_t current_subperiod = get_gpos_current_subperiod();
+ 
    if(current_subperiod == 0 || current_subperiod > number_of_subperiods) return 0;
+
+   // On starting new vesting period, all votes become zero until someone votes, To avoid a situation of zero votes, 
+   // changes were done to roll in GPOS rules, the vesting factor will be 1 for whoever votes in 6th sub-period of last vesting period
+   // BLOCKBACK-174 fix
+   if(current_subperiod == 1 && this->head_block_time() >= HARDFORK_GPOS_TIME + vesting_period)   //Applicable only from 2nd vesting period
+   {
+      if(last_date_voted > period_start - vesting_subperiod)
+         return 1;
+   }
+
    if(last_date_voted < period_start) return 0;
 
    double numerator = number_of_subperiods;
@@ -853,7 +885,7 @@ void rolling_period_start(database& db)
       auto vesting_period = db.get_global_properties().parameters.gpos_period();
 
       auto now = db.head_block_time();
-      if(now.sec_since_epoch() > (period_start + vesting_period))
+      if(now.sec_since_epoch() >= (period_start + vesting_period))
       {
          // roll
          db.modify(db.get_global_properties(), [now](global_property_object& p) {
@@ -1114,8 +1146,8 @@ void schedule_pending_dividend_balances(database& db,
                         dlog("Crediting committee_account with ${amount}",
                              ("amount", asset(full_shares_to_credit - shares_to_credit, payout_asset_type)));
                         db.adjust_balance(dividend_data.dividend_distribution_account,
-                                          -(full_shares_to_credit - shares_to_credit));
-                        db.adjust_balance(account_id_type(0), full_shares_to_credit - shares_to_credit);
+                                          -asset(full_shares_to_credit - shares_to_credit, payout_asset_type));
+                        db.adjust_balance(account_id_type(0), asset(full_shares_to_credit - shares_to_credit, payout_asset_type));
                      }
 
                      remaining_amount_to_distribute = credit_account(db,
@@ -1415,10 +1447,10 @@ void database::perform_chain_maintenance(const signed_block& next_block, const g
    distribute_fba_balances(*this);
    create_buyback_orders(*this);
 
-   rolling_period_start(*this);
-
    process_dividend_assets(*this);
 
+   rolling_period_start(*this);
+
    struct vote_tally_helper {
       database& d;
       const global_property_object& props;
@@ -1587,6 +1619,12 @@ void database::perform_chain_maintenance(const signed_block& next_block, const g
             p.pending_parameters->extensions.value.permitted_betting_odds_increments = p.parameters.extensions.value.permitted_betting_odds_increments;
          if( !p.pending_parameters->extensions.value.live_betting_delay_time.valid() )
             p.pending_parameters->extensions.value.live_betting_delay_time = p.parameters.extensions.value.live_betting_delay_time;
+         if( !p.pending_parameters->extensions.value.gpos_period.valid() )
+            p.pending_parameters->extensions.value.gpos_period = p.parameters.extensions.value.gpos_period;
+         if( !p.pending_parameters->extensions.value.gpos_subperiod.valid() )
+            p.pending_parameters->extensions.value.gpos_subperiod = p.parameters.extensions.value.gpos_subperiod;
+         if( !p.pending_parameters->extensions.value.gpos_vesting_lockin_period.valid() )
+            p.pending_parameters->extensions.value.gpos_vesting_lockin_period = p.parameters.extensions.value.gpos_vesting_lockin_period;                              
          p.parameters = std::move(*p.pending_parameters);
          p.pending_parameters.reset();
       }
diff --git a/libraries/chain/hardfork.d/GPOS.hf b/libraries/chain/hardfork.d/GPOS.hf
index e109a8ad..f86dbc22 100644
--- a/libraries/chain/hardfork.d/GPOS.hf
+++ b/libraries/chain/hardfork.d/GPOS.hf
@@ -1,4 +1,4 @@
-// GPOS HARDFORK Friday, March 15, 2019 11:57:28 PM
+// GPOS HARDFORK Tuesday, October 22, 2019 05:00:00 AM GMT
 #ifndef HARDFORK_GPOS_TIME
-#define HARDFORK_GPOS_TIME (fc::time_point_sec( 1552694248 ))
+#define HARDFORK_GPOS_TIME (fc::time_point_sec( 1571720400 ))
 #endif
diff --git a/libraries/chain/include/graphene/chain/database.hpp b/libraries/chain/include/graphene/chain/database.hpp
index dee3d006..571be20a 100644
--- a/libraries/chain/include/graphene/chain/database.hpp
+++ b/libraries/chain/include/graphene/chain/database.hpp
@@ -525,6 +525,7 @@ namespace graphene { namespace chain {
 
          public:
             double calculate_vesting_factor(const account_object& stake_account);
+            uint32_t get_gpos_current_subperiod();
 
          template<class... Types>
          void perform_account_maintenance(std::tuple<Types...> helpers);
diff --git a/libraries/chain/include/graphene/chain/protocol/account.hpp b/libraries/chain/include/graphene/chain/protocol/account.hpp
index 6d13a4d3..6a8aa20c 100644
--- a/libraries/chain/include/graphene/chain/protocol/account.hpp
+++ b/libraries/chain/include/graphene/chain/protocol/account.hpp
@@ -140,6 +140,7 @@ namespace graphene { namespace chain {
          optional< void_t >            null_ext;
          optional< special_authority > owner_special_authority;
          optional< special_authority > active_special_authority;
+         optional< bool >              update_last_voting_time = false;
       };
 
       struct fee_parameters_type
@@ -295,7 +296,7 @@ FC_REFLECT( graphene::chain::account_create_operation,
             (name)(owner)(active)(options)(extensions)
           )
 
-FC_REFLECT(graphene::chain::account_update_operation::ext, (null_ext)(owner_special_authority)(active_special_authority) )
+FC_REFLECT(graphene::chain::account_update_operation::ext, (null_ext)(owner_special_authority)(active_special_authority)(update_last_voting_time) )
 FC_REFLECT( graphene::chain::account_update_operation,
             (fee)(account)(owner)(active)(new_options)(extensions)
           )
diff --git a/libraries/chain/include/graphene/chain/protocol/vesting.hpp b/libraries/chain/include/graphene/chain/protocol/vesting.hpp
index abe380a7..2a861b2a 100644
--- a/libraries/chain/include/graphene/chain/protocol/vesting.hpp
+++ b/libraries/chain/include/graphene/chain/protocol/vesting.hpp
@@ -28,6 +28,16 @@ namespace graphene { namespace chain {
 
    enum class vesting_balance_type { normal, gpos };
 
+   inline std::string get_vesting_balance_type(vesting_balance_type type) {
+      switch (type) {
+         case vesting_balance_type::normal:
+            return "NORMAL";
+         case vesting_balance_type::gpos:
+         default:
+            return "GPOS";
+      }
+   }
+
    struct linear_vesting_policy_initializer
    {
       /** while vesting begins on begin_timestamp, none may be claimed before vesting_cliff_seconds have passed */
@@ -123,4 +133,3 @@ FC_REFLECT(graphene::chain::cdd_vesting_policy_initializer, (start_claim)(vestin
 FC_REFLECT_TYPENAME( graphene::chain::vesting_policy_initializer )
 
 FC_REFLECT_ENUM( graphene::chain::vesting_balance_type, (normal)(gpos) )
-
diff --git a/libraries/chain/vesting_balance_evaluator.cpp b/libraries/chain/vesting_balance_evaluator.cpp
index d0f3c345..28282b87 100644
--- a/libraries/chain/vesting_balance_evaluator.cpp
+++ b/libraries/chain/vesting_balance_evaluator.cpp
@@ -45,7 +45,6 @@ void_result vesting_balance_create_evaluator::do_evaluate( const vesting_balance
    if(d.head_block_time() < HARDFORK_GPOS_TIME) // Todo: can be removed after gpos hf time pass
       FC_ASSERT( op.balance_type == vesting_balance_type::normal);
 
-
    return void_result();
 } FC_CAPTURE_AND_RETHROW( (op) ) }
 
@@ -146,7 +145,8 @@ void_result vesting_balance_withdraw_evaluator::do_evaluate( const vesting_balan
 
    const vesting_balance_object& vbo = op.vesting_balance( d );
    FC_ASSERT( op.owner == vbo.owner, "", ("op.owner", op.owner)("vbo.owner", vbo.owner) );
-   FC_ASSERT( vbo.is_withdraw_allowed( now, op.amount ), "", ("now", now)("op", op)("vbo", vbo) );
+   FC_ASSERT( vbo.is_withdraw_allowed( now, op.amount ), "${balance_type} Vested Balance cannot be withdrawn during the locking period", 
+         ("balance_type", get_vesting_balance_type(vbo.balance_type))("now", now)("op", op)("vbo", vbo) );
    assert( op.amount <= vbo.balance );      // is_withdraw_allowed should fail before this check is reached
 
    /* const account_object& owner_account =  op.owner( d ); */
diff --git a/libraries/wallet/include/graphene/wallet/wallet.hpp b/libraries/wallet/include/graphene/wallet/wallet.hpp
index ac54f258..d6082564 100644
--- a/libraries/wallet/include/graphene/wallet/wallet.hpp
+++ b/libraries/wallet/include/graphene/wallet/wallet.hpp
@@ -1300,6 +1300,12 @@ class wallet_api
        */
       witness_object get_witness(string owner_account);
 
+      /** Returns true if the account is witness, false otherwise
+       * @param owner_account the name or id of the witness account owner, or the id of the witness
+       * @returns true if account is witness, false otherwise
+       */
+      bool is_witness(string owner_account);
+
       /** Returns information about the given committee_member.
        * @param owner_account the name or id of the committee_member account owner, or the id of the committee_member
        * @returns the information about the committee_member stored in the block chain
@@ -2041,6 +2047,7 @@ FC_API( graphene::wallet::wallet_api,
         (whitelist_account)
         (create_committee_member)
         (get_witness)
+        (is_witness)
         (get_committee_member)
         (list_witnesses)
         (list_committee_members)
diff --git a/libraries/wallet/wallet.cpp b/libraries/wallet/wallet.cpp
index 4469e598..f1b6576e 100644
--- a/libraries/wallet/wallet.cpp
+++ b/libraries/wallet/wallet.cpp
@@ -1779,6 +1779,42 @@ public:
       FC_CAPTURE_AND_RETHROW( (owner_account) )
    }
 
+   bool is_witness(string owner_account)
+   {
+      try
+      {
+         fc::optional<witness_id_type> witness_id = maybe_id<witness_id_type>(owner_account);
+         if (witness_id)
+         {
+            std::vector<witness_id_type> ids_to_get;
+            ids_to_get.push_back(*witness_id);
+            std::vector<fc::optional<witness_object>> witness_objects = _remote_db->get_witnesses(ids_to_get);
+            if (witness_objects.front())
+               return true;
+            else
+               return false;
+         }
+         else
+         {
+            // then maybe it's the owner account
+            try
+            {
+               account_id_type owner_account_id = get_account_id(owner_account);
+               fc::optional<witness_object> witness = _remote_db->get_witness_by_account(owner_account_id);
+               if (witness)
+                  return true;
+               else
+                  return false;
+            }
+            catch (const fc::exception&)
+            {
+               return false;
+            }
+         }
+      }
+      FC_CAPTURE_AND_RETHROW( (owner_account) )
+   }
+
    committee_member_object get_committee_member(string owner_account)
    {
       try
@@ -2027,9 +2063,14 @@ public:
       fc::optional<vesting_balance_id_type> vbid = maybe_id<vesting_balance_id_type>(witness_name);
       if( !vbid )
       {
-         witness_object wit = get_witness( witness_name );
-         FC_ASSERT( wit.pay_vb );
-         vbid = wit.pay_vb;
+         if (is_witness(witness_name)) 
+         {
+            witness_object wit = get_witness( witness_name );
+            FC_ASSERT( wit.pay_vb, "Account ${account} has no core Token ${TOKEN} vested and thus its not allowed to withdraw.", ("account", witness_name)("TOKEN", GRAPHENE_SYMBOL));
+            vbid = wit.pay_vb;
+         }
+         else 
+            FC_THROW("Account ${account} has no core Token ${TOKEN} vested and thus its not allowed to withdraw.", ("account", witness_name)("TOKEN", GRAPHENE_SYMBOL));
       }
 
       vesting_balance_object vbo = get_object< vesting_balance_object >( *vbid );
@@ -2069,12 +2110,8 @@ public:
             acct_id = get_account( account_name ).id;
 
          vbos = _remote_db->get_vesting_balances( *acct_id );
-         if( vbos.size() == 0 )
-         {
-            witness_object wit = get_witness( account_name );
-            FC_ASSERT( wit.pay_vb );
-            vbid = wit.pay_vb;
-         }
+         if( vbos.size() == 0 ) 
+            FC_THROW("Account ${account} has no core TOKEN vested and thus its not allowed to withdraw.", ("account", account_name));
       }
 
       //whether it is a witness or user, keep it in a container and iterate over to process all vesting balances and types 
@@ -2138,18 +2175,29 @@ public:
 
       vbo_iter = std::find_if(vbo_info.begin(), vbo_info.end(), [](vesting_balance_object_with_info const& obj){return obj.balance_type == vesting_balance_type::gpos;});
       if( vbo_info.size() == 0 ||  vbo_iter == vbo_info.end())
-         FC_THROW("Account *** ${account} *** have insufficient or 0 vested balance(GPOS) to vote", ("account", voting_account));
+         FC_THROW("Account ${account} has no core Token ${TOKEN} vested and thus she will not be allowed to vote for the committee member", ("account", voting_account)("TOKEN", GRAPHENE_SYMBOL));
 
       account_object voting_account_object = get_account(voting_account);
       account_id_type committee_member_owner_account_id = get_account_id(committee_member);
       fc::optional<committee_member_object> committee_member_obj = _remote_db->get_committee_member_by_account(committee_member_owner_account_id);
       if (!committee_member_obj)
          FC_THROW("Account ${committee_member} is not registered as a committee_member", ("committee_member", committee_member));
+
+      bool update_vote_time = false;
+
       if (approve)
       {
+         account_id_type stake_account = get_account_id(voting_account);
+         const auto gpos_info = _remote_db->get_gpos_info(stake_account);
+         const auto vesting_subperiod = _remote_db->get_global_properties().parameters.gpos_subperiod();
+         const auto gpos_start_time = fc::time_point_sec(_remote_db->get_global_properties().parameters.gpos_period_start());
+         const auto subperiod_start_time = gpos_start_time.sec_since_epoch() + (gpos_info.current_subperiod - 1) * vesting_subperiod;
+
          auto insert_result = voting_account_object.options.votes.insert(committee_member_obj->vote_id);
-         if (!insert_result.second)
-            FC_THROW("Account ${account} was already voting for committee_member ${committee_member}", ("account", voting_account)("committee_member", committee_member));
+         if (!insert_result.second && (gpos_info.last_voted_time.sec_since_epoch() >= subperiod_start_time))
+            FC_THROW("Account ${account} was already voting for committee_member ${committee_member} in the current GPOS sub-period", ("account", voting_account)("committee_member", committee_member));
+         else
+            update_vote_time = true;   //Allow user to vote in each sub-period(Update voting time, which is reference in calculating VF)
       }
       else
       {
@@ -2160,6 +2208,7 @@ public:
       account_update_operation account_update_op;
       account_update_op.account = voting_account_object.id;
       account_update_op.new_options = voting_account_object.options;
+      account_update_op.extensions.value.update_last_voting_time = update_vote_time;
 
       signed_transaction tx;
       tx.operations.push_back( account_update_op );
@@ -2179,28 +2228,41 @@ public:
 
       vbo_iter = std::find_if(vbo_info.begin(), vbo_info.end(), [](vesting_balance_object_with_info const& obj){return obj.balance_type == vesting_balance_type::gpos;});
       if( vbo_info.size() == 0 ||  vbo_iter == vbo_info.end())
-         FC_THROW("Account *** ${account} *** have insufficient or 0 vested balance(GPOS) to vote", ("account", voting_account));
+         FC_THROW("Account ${account} has no core Token ${TOKEN} vested and thus she will not be allowed to vote for the witness", ("account", voting_account)("TOKEN", GRAPHENE_SYMBOL));
 
       account_object voting_account_object = get_account(voting_account);
       account_id_type witness_owner_account_id = get_account_id(witness);
+      
       fc::optional<witness_object> witness_obj = _remote_db->get_witness_by_account(witness_owner_account_id);
       if (!witness_obj)
          FC_THROW("Account ${witness} is not registered as a witness", ("witness", witness));
+
+      bool update_vote_time = false;
       if (approve)
       {
+         account_id_type stake_account = get_account_id(voting_account);
+         const auto gpos_info = _remote_db->get_gpos_info(stake_account);
+         const auto vesting_subperiod = _remote_db->get_global_properties().parameters.gpos_subperiod();
+         const auto gpos_start_time = fc::time_point_sec(_remote_db->get_global_properties().parameters.gpos_period_start());
+         const auto subperiod_start_time = gpos_start_time.sec_since_epoch() + (gpos_info.current_subperiod - 1) * vesting_subperiod;
+
          auto insert_result = voting_account_object.options.votes.insert(witness_obj->vote_id);
-         if (!insert_result.second)
-            FC_THROW("Account ${account} was already voting for witness ${witness}", ("account", voting_account)("witness", witness));
+         if (!insert_result.second && (gpos_info.last_voted_time.sec_since_epoch() >= subperiod_start_time))
+            FC_THROW("Account ${account} was already voting for witness ${witness} in the current GPOS sub-period", ("account", voting_account)("witness", witness));
+         else
+            update_vote_time = true;   //Allow user to vote in each sub-period(Update voting time, which is reference in calculating VF)
       }
       else
       {
          unsigned votes_removed = voting_account_object.options.votes.erase(witness_obj->vote_id);
          if (!votes_removed)
-            FC_THROW("Account ${account} is already not voting for witness ${witness}", ("account", voting_account)("witness", witness));
+            FC_THROW("Account ${account} has not voted for witness ${witness}", ("account", voting_account)("witness", witness));
       }
+      
       account_update_operation account_update_op;
       account_update_op.account = voting_account_object.id;
       account_update_op.new_options = voting_account_object.options;
+      account_update_op.extensions.value.update_last_voting_time = update_vote_time;
 
       signed_transaction tx;
       tx.operations.push_back( account_update_op );
@@ -4213,6 +4275,11 @@ witness_object wallet_api::get_witness(string owner_account)
    return my->get_witness(owner_account);
 }
 
+bool wallet_api::is_witness(string owner_account)
+{
+   return my->is_witness(owner_account);
+}
+
 committee_member_object wallet_api::get_committee_member(string owner_account)
 {
    return my->get_committee_member(owner_account);
diff --git a/tests/tests/gpos_tests.cpp b/tests/tests/gpos_tests.cpp
index 2f8f7014..196fe7ee 100644
--- a/tests/tests/gpos_tests.cpp
+++ b/tests/tests/gpos_tests.cpp
@@ -95,12 +95,22 @@ struct gpos_fixture: database_fixture
       BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_subperiod(), vesting_subperiod);
       BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period_start(), period_start.sec_since_epoch());
    }
+
+   void update_maintenance_interval(uint32_t new_interval)
+   {
+      db.modify(db.get_global_properties(), [new_interval](global_property_object& p) {
+         p.parameters.maintenance_interval = new_interval;
+      });
+      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.maintenance_interval, new_interval);
+   }
+
    void vote_for(const account_id_type account_id, const vote_id_type vote_for, const fc::ecc::private_key& key)
    {
       account_update_operation op;
       op.account = account_id;
       op.new_options = account_id(db).options;
       op.new_options->votes.insert(vote_for);
+      op.extensions.value.update_last_voting_time = true;
       trx.operations.push_back(op);
       set_expiration(db, trx);
       trx.validate();
@@ -339,11 +349,175 @@ BOOST_AUTO_TEST_CASE( dividends )
    }
 }
 
+BOOST_AUTO_TEST_CASE( gpos_basic_dividend_distribution_to_core_asset )
+{
+   using namespace graphene;
+   ACTORS((alice)(bob)(carol)(dave));
+   try {
+      const auto& core = asset_id_type()(db);
+      BOOST_TEST_MESSAGE("Creating test asset");
+      {
+         asset_create_operation creator;
+         creator.issuer = account_id_type();
+         creator.fee = asset();
+         creator.symbol = "TESTB";
+         creator.common_options.max_supply = 100000000;
+         creator.precision = 2;
+         creator.common_options.market_fee_percent = GRAPHENE_MAX_MARKET_FEE_PERCENT/100; /*1%*/
+         creator.common_options.issuer_permissions = UIA_ASSET_ISSUER_PERMISSION_MASK;
+         creator.common_options.flags = charge_market_fee;
+         creator.common_options.core_exchange_rate = price({asset(2),asset(1,asset_id_type(1))});
+         trx.operations.push_back(std::move(creator));
+         set_expiration(db, trx);
+         PUSH_TX( db, trx, ~0 );
+         trx.operations.clear();
+      }
+      
+      // pass hardfork
+      generate_blocks( HARDFORK_GPOS_TIME );
+      generate_block();
+
+      const auto& dividend_holder_asset_object = asset_id_type(0)(db);
+      const auto& dividend_data = dividend_holder_asset_object.dividend_data(db);
+      const account_object& dividend_distribution_account = dividend_data.dividend_distribution_account(db);
+      const account_object& alice = get_account("alice");
+      const account_object& bob = get_account("bob");
+      const account_object& carol = get_account("carol");
+      const account_object& dave = get_account("dave");
+      const auto& test_asset_object = get_asset("TESTB");
+
+      auto issue_asset_to_account = [&](const asset_object& asset_to_issue, const account_object& destination_account, int64_t amount_to_issue)
+      {
+         asset_issue_operation op;
+         op.issuer = asset_to_issue.issuer;
+         op.asset_to_issue = asset(amount_to_issue, asset_to_issue.id);
+         op.issue_to_account = destination_account.id;
+         trx.operations.push_back( op );
+         set_expiration(db, trx);
+         PUSH_TX( db, trx, ~0 );
+         trx.operations.clear();
+      };
+
+      auto verify_pending_balance = [&](const account_object& holder_account_obj, const asset_object& payout_asset_obj, int64_t expected_balance) {
+         int64_t pending_balance = get_dividend_pending_payout_balance(dividend_holder_asset_object.id,
+                                                                       holder_account_obj.id,
+                                                                       payout_asset_obj.id);
+         BOOST_CHECK_EQUAL(pending_balance, expected_balance);
+      };
+
+      auto advance_to_next_payout_time = [&]() {
+         // Advance to the next upcoming payout time
+         BOOST_REQUIRE(dividend_data.options.next_payout_time);
+         fc::time_point_sec next_payout_scheduled_time = *dividend_data.options.next_payout_time;
+         idump((next_payout_scheduled_time));
+         // generate blocks up to the next scheduled time
+         generate_blocks(next_payout_scheduled_time);
+         // if the scheduled time fell on a maintenance interval, then we should have paid out.
+         // if not, we need to advance to the next maintenance interval to trigger the payout
+         if (dividend_data.options.next_payout_time)
+         {
+            // we know there was a next_payout_time set when we entered this, so if
+            // it has been cleared, we must have already processed payouts, no need to
+            // further advance time.
+            BOOST_REQUIRE(dividend_data.options.next_payout_time);
+            if (*dividend_data.options.next_payout_time == next_payout_scheduled_time)
+               generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+            generate_block();   // get the maintenance skip slots out of the way
+         }
+         idump((db.head_block_time()));
+      };
+
+      // the first test will be testing pending balances, so we need to hit a
+      // maintenance interval that isn't the payout interval.  Payout is
+      // every 3 days, maintenance interval is every 1 day.
+      advance_to_next_payout_time();
+
+      // Set up the first test, issue alice, bob, and carol, and dave each 1/4 of the total
+      // supply of the core asset.
+      // Then deposit 400 TEST in the distribution account, and see that they
+      // each are credited 100 TEST.
+      transfer( committee_account(db), alice, asset( 250000000000000 ) );
+      transfer( committee_account(db), bob,   asset( 250000000000000 ) );
+      transfer( committee_account(db), carol, asset( 250000000000000 ) );
+      transfer( committee_account(db), dave,  asset( 250000000000000 ) );
+
+      // create vesting balance
+      // bob has not vested anything
+      create_vesting(alice_id, core.amount(25000000), vesting_balance_type::gpos);
+      create_vesting(carol_id, core.amount(25000000), vesting_balance_type::gpos);
+      create_vesting(dave_id, core.amount(25000000), vesting_balance_type::gpos);
+
+      // need to vote to get paid
+      // carol doesn't participate in voting
+      auto witness1 = witness_id_type(1)(db);
+      vote_for(alice_id, witness1.vote_id, alice_private_key);
+      vote_for(bob_id, witness1.vote_id, bob_private_key);
+      vote_for(dave_id, witness1.vote_id, dave_private_key);
+
+      // issuing 30000 TESTB to the dividend account
+      // alice and dave should receive 10000 TESTB as they have gpos vesting and 
+      // participated in voting
+      // bob should not receive any TESTB as he doesn't have gpos vested
+      // carol should not receive any TESTB as she doesn't participated in voting
+      // remaining 10000 TESTB should be deposited in commitee_accoount. 
+      BOOST_TEST_MESSAGE("Issuing 30000 TESTB to the dividend account");
+      issue_asset_to_account(test_asset_object, dividend_distribution_account, 30000);
+
+      generate_block();
+
+      BOOST_TEST_MESSAGE( "Generating blocks until next maintenance interval" );
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      generate_block();   // get the maintenance skip slots out of the way
+
+      verify_pending_balance(alice, test_asset_object, 10000);
+      verify_pending_balance(bob, test_asset_object, 0);
+      verify_pending_balance(carol, test_asset_object, 0);
+      verify_pending_balance(dave, test_asset_object, 10000);
+
+      advance_to_next_payout_time();
+
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      generate_block();   // get the maintenance skip slots out of the way
+
+      auto verify_dividend_payout_operations = [&](const account_object& destination_account, const asset& expected_payout)
+      {
+         BOOST_TEST_MESSAGE("Verifying the virtual op was created");
+         const account_transaction_history_index& hist_idx = db.get_index_type<account_transaction_history_index>();
+         auto account_history_range = hist_idx.indices().get<by_seq>().equal_range(boost::make_tuple(destination_account.id));
+         BOOST_REQUIRE(account_history_range.first != account_history_range.second);
+         const operation_history_object& history_object = std::prev(account_history_range.second)->operation_id(db);
+         const asset_dividend_distribution_operation& distribution_operation = history_object.op.get<asset_dividend_distribution_operation>();
+         BOOST_CHECK(distribution_operation.account_id == destination_account.id);
+         BOOST_CHECK(std::find(distribution_operation.amounts.begin(), distribution_operation.amounts.end(), expected_payout)
+            != distribution_operation.amounts.end());
+      };
+
+      BOOST_TEST_MESSAGE("Verifying the payouts");
+      BOOST_CHECK_EQUAL(get_balance(alice, test_asset_object), 10000);
+      verify_dividend_payout_operations(alice, asset(10000, test_asset_object.id));
+      verify_pending_balance(alice, test_asset_object, 0);
+
+      BOOST_CHECK_EQUAL(get_balance(bob, test_asset_object), 0);
+      verify_pending_balance(bob, test_asset_object, 0);
+
+      BOOST_CHECK_EQUAL(get_balance(carol, test_asset_object), 0);
+      verify_pending_balance(carol, test_asset_object, 0);
+
+      BOOST_CHECK_EQUAL(get_balance(dave, test_asset_object), 10000);
+      verify_dividend_payout_operations(dave, asset(10000, test_asset_object.id));
+      verify_pending_balance(dave, test_asset_object, 0);
+
+      BOOST_CHECK_EQUAL(get_balance(account_id_type(0)(db), test_asset_object), 10000);
+   } catch(fc::exception& e) {
+      edump((e.to_detail_string()));
+      throw;
+   }   
+}
+
 BOOST_AUTO_TEST_CASE( voting )
 {
    ACTORS((alice)(bob));
    try {
-
       // move to hardfork
       generate_blocks( HARDFORK_GPOS_TIME );
       generate_block();
@@ -389,65 +563,97 @@ BOOST_AUTO_TEST_CASE( voting )
       auto witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness2.total_votes, 0);
 
-      // vote for witness1
+      // vote for witness1 and witness2 - sub-period 1
       vote_for(alice_id, witness1.vote_id, alice_private_key);
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
 
       // go to maint
       generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
 
       // vote is the same as amount in the first subperiod since voting
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness1.total_votes, 100);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       advance_x_maint(10);
 
+      //Bob votes for witness2 - sub-period 2
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      // go to maint
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
       // vote decay as time pass
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
+
       BOOST_CHECK_EQUAL(witness1.total_votes, 83);
-
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
+      
       advance_x_maint(10);
-
+      //Bob votes for witness2 - sub-period 3
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
       // decay more
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness1.total_votes, 66);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       advance_x_maint(10);
-
-      // more
+      
+      // Bob votes for witness2 - sub-period 4
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      // decay more
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness1.total_votes, 50);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       advance_x_maint(10);
-
-      // more
+      
+      // Bob votes for witness2 - sub-period 5
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      // decay more
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
+
       BOOST_CHECK_EQUAL(witness1.total_votes, 33);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       advance_x_maint(10);
-
-      // more
+      
+      // Bob votes for witness2 - sub-period 6
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      // decay more
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness1.total_votes, 16);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       // we are still in gpos period 1
       BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period_start(), now.sec_since_epoch());
 
-      advance_x_maint(10);
-
-      // until 0
-      witness1 = witness_id_type(1)(db);
-      BOOST_CHECK_EQUAL(witness1.total_votes, 0);
-
-      // a new GPOS period is in but vote from user is before the start so his voting power is 0
+      advance_x_maint(5);
+      // a new GPOS period is in but vote from user is before the start. Whoever votes in 6th sub-period, votes will carry
       now = db.head_block_time();
       BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period_start(), now.sec_since_epoch());
 
       generate_block();
 
+      // we are in the second GPOS period, at subperiod 1,
       witness1 = witness_id_type(1)(db);
+      witness2 = witness_id_type(2)(db);
       BOOST_CHECK_EQUAL(witness1.total_votes, 0);
+      //It's critical here, since bob votes in 6th sub-period of last vesting period, witness2 should retain his votes
+      BOOST_CHECK_EQUAL(witness2.total_votes, 100);   
 
-      // we are in the second GPOS period, at subperiod 2, lets vote here
+
+      // lets vote here from alice to generate votes for witness 1
+      //vote from bob to reatin VF 1
+      vote_for(alice_id, witness1.vote_id, alice_private_key);
       vote_for(bob_id, witness2.vote_id, bob_private_key);
       generate_block();
 
@@ -457,7 +663,7 @@ BOOST_AUTO_TEST_CASE( voting )
       witness1 = witness_id_type(1)(db);
       witness2 = witness_id_type(2)(db);
 
-      BOOST_CHECK_EQUAL(witness1.total_votes, 0);
+      BOOST_CHECK_EQUAL(witness1.total_votes, 100);
       BOOST_CHECK_EQUAL(witness2.total_votes, 100);
 
       advance_x_maint(10);
@@ -465,16 +671,19 @@ BOOST_AUTO_TEST_CASE( voting )
       witness1 = witness_id_type(1)(db);
       witness2 = witness_id_type(2)(db);
 
-      BOOST_CHECK_EQUAL(witness1.total_votes, 0);
+      BOOST_CHECK_EQUAL(witness1.total_votes, 83);
       BOOST_CHECK_EQUAL(witness2.total_votes, 83);
 
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+      generate_block();
+
       advance_x_maint(10);
 
       witness1 = witness_id_type(1)(db);
       witness2 = witness_id_type(2)(db);
 
-      BOOST_CHECK_EQUAL(witness1.total_votes, 0);
-      BOOST_CHECK_EQUAL(witness2.total_votes, 66);
+      BOOST_CHECK_EQUAL(witness1.total_votes, 66);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 83);
 
       // alice votes again, now for witness 2, her vote worth 100 now
       vote_for(alice_id, witness2.vote_id, alice_private_key);
@@ -484,7 +693,7 @@ BOOST_AUTO_TEST_CASE( voting )
       witness2 = witness_id_type(2)(db);
 
       BOOST_CHECK_EQUAL(witness1.total_votes, 100);
-      BOOST_CHECK_EQUAL(witness2.total_votes, 166);
+      BOOST_CHECK_EQUAL(witness2.total_votes, 183);
 
    }
    catch (fc::exception &e) {
@@ -497,33 +706,32 @@ BOOST_AUTO_TEST_CASE( rolling_period_start )
 {
    // period start rolls automatically after HF
    try {
-      // advance to HF
-      generate_blocks(HARDFORK_GPOS_TIME);
-      generate_block();
-
       // update default gpos global parameters to make this thing faster
-      auto now = db.head_block_time();
-      update_gpos_global(518400, 86400, now);
+      update_gpos_global(518400, 86400, HARDFORK_GPOS_TIME);
+      generate_blocks(HARDFORK_GPOS_TIME);
+      update_maintenance_interval(3600);  //update maintenance interval to 1hr to evaluate sub-periods
+      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.maintenance_interval, 3600);
 
+      auto vesting_period_1 = db.get_global_properties().parameters.gpos_period_start();
+            
+      auto now = db.head_block_time();
       // moving outside period:
       while( db.head_block_time() <= now + fc::days(6) )
       {
          generate_block();
       }
-      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
-
-      // rolling is here so getting the new now
-      now = db.head_block_time();
       generate_block();
-
-      // period start rolled
-      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period_start(), now.sec_since_epoch());
+      auto vesting_period_2 = db.get_global_properties().parameters.gpos_period_start();
+     
+     //difference between start of two consecutive vesting periods should be 6 days 
+      BOOST_CHECK_EQUAL(vesting_period_1 + 518400, vesting_period_2); 
    }
    catch (fc::exception &e) {
       edump((e.to_detail_string()));
       throw;
    }
 }
+
 BOOST_AUTO_TEST_CASE( worker_dividends_voting )
 {
    try {
@@ -833,8 +1041,101 @@ BOOST_AUTO_TEST_CASE( competing_proposals )
 */
 BOOST_AUTO_TEST_CASE( proxy_voting )
 {
+   ACTORS((alice)(bob));
    try {
+      // move to hardfork
+      generate_blocks( HARDFORK_GPOS_TIME );
+      generate_block();
 
+      // database api
+      graphene::app::database_api db_api(db);
+
+      const auto& core = asset_id_type()(db);
+
+      // send some asset to alice and bob
+      transfer( committee_account, alice_id, core.amount( 1000 ) );
+      transfer( committee_account, bob_id, core.amount( 1000 ) );
+      generate_block();
+
+      // add some vesting to alice and bob
+      create_vesting(alice_id, core.amount(100), vesting_balance_type::gpos);
+      generate_block();
+
+      // total balance is 100 rest of data at 0
+      auto gpos_info = db_api.get_gpos_info(alice_id);
+      BOOST_CHECK_EQUAL(gpos_info.vesting_factor, 0);
+      BOOST_CHECK_EQUAL(gpos_info.award.amount.value, 0);
+      BOOST_CHECK_EQUAL(gpos_info.total_amount.value, 100);
+
+      create_vesting(bob_id, core.amount(100), vesting_balance_type::gpos);
+      generate_block();
+
+      gpos_info = db_api.get_gpos_info(bob_id);
+      BOOST_CHECK_EQUAL(gpos_info.vesting_factor, 0);
+      BOOST_CHECK_EQUAL(gpos_info.award.amount.value, 0);
+      BOOST_CHECK_EQUAL(gpos_info.total_amount.value, 200);
+
+      auto now = db.head_block_time();
+      update_gpos_global(518400, 86400, now);
+
+      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period(), 518400);
+      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_subperiod(), 86400);
+      BOOST_CHECK_EQUAL(db.get_global_properties().parameters.gpos_period_start(), now.sec_since_epoch());
+
+      // alice assign bob as voting account
+      graphene::chain::account_update_operation op;
+      op.account = alice_id;
+      op.new_options = alice_id(db).options;
+      op.new_options->voting_account = bob_id;
+      trx.operations.push_back(op);
+      set_expiration(db, trx);
+      trx.validate();
+      sign(trx, alice_private_key);
+      PUSH_TX( db, trx, ~0 );
+      trx.clear();
+
+      generate_block();
+
+      // vote for witness1
+      auto witness1 = witness_id_type(1)(db);
+      vote_for(bob_id, witness1.vote_id, bob_private_key);
+      
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      
+      // check vesting factor of current subperiod
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(alice_id).vesting_factor, 1);
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(bob_id).vesting_factor, 1);
+      
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      generate_block();
+
+      // GPOS 2nd subperiod started.
+      // vesting factor decay
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(alice_id).vesting_factor, 0.83333333333333337);
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(bob_id).vesting_factor, 0.83333333333333337);
+      
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      generate_block();
+
+      // GPOS 3rd subperiod started
+      // vesting factor decay
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(alice_id).vesting_factor, 0.66666666666666663);
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(bob_id).vesting_factor, 0.66666666666666663);
+
+      // vote for witness2
+      auto witness2 = witness_id_type(2)(db);
+      vote_for(bob_id, witness2.vote_id, bob_private_key);
+
+      // vesting factor should be 1 for both alice and bob for the current subperiod
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(alice_id).vesting_factor, 1);
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(bob_id).vesting_factor, 1);
+
+      generate_blocks(db.get_dynamic_global_properties().next_maintenance_time);
+      generate_block();
+
+      // vesting factor decay
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(alice_id).vesting_factor, 0.83333333333333337);
+      BOOST_CHECK_EQUAL(db_api.get_gpos_info(bob_id).vesting_factor, 0.83333333333333337);
    }
    catch (fc::exception &e) {
       edump((e.to_detail_string()));
@@ -852,11 +1153,11 @@ BOOST_AUTO_TEST_CASE( no_proposal )
       throw;
    }
 }
+
 BOOST_AUTO_TEST_CASE( database_api )
 {
    ACTORS((alice)(bob));
    try {
-
       // move to hardfork
       generate_blocks( HARDFORK_GPOS_TIME );
       generate_block();