diff --git a/libraries/chain/database.cpp b/libraries/chain/database.cpp
index a2e16adb40..a6aec7c88e 100644
--- a/libraries/chain/database.cpp
+++ b/libraries/chain/database.cpp
@@ -2733,7 +2733,7 @@ void database::apply_block( const signed_block& next_block, uint32_t skip )
               | skip_block_size_check
               | skip_tapos_check
               | skip_authority_check
-              | skip_merkle_check
+              /* | skip_merkle_check While blockchain is being downloaded, txs need to be validated against block headers */
               | skip_undo_history_check
               | skip_witness_schedule_check
               | skip_validate
diff --git a/libraries/chain/include/steemit/chain/config.hpp b/libraries/chain/include/steemit/chain/config.hpp
index 20ee7ac543..53d9a91bce 100644
--- a/libraries/chain/include/steemit/chain/config.hpp
+++ b/libraries/chain/include/steemit/chain/config.hpp
@@ -3,7 +3,7 @@
  */
 #pragma once
 
-#define STEEMIT_BLOCKCHAIN_VERSION              ( version(0, 14, 2) )
+#define STEEMIT_BLOCKCHAIN_VERSION              ( version(0, 14, 3) )
 #define STEEMIT_BLOCKCHAIN_HARDFORK_VERSION     ( hardfork_version( STEEMIT_BLOCKCHAIN_VERSION ) )
 
 #ifdef IS_TEST_NET
diff --git a/libraries/chain/steem_evaluator.cpp b/libraries/chain/steem_evaluator.cpp
index 9eef5944f6..6dd95162a1 100644
--- a/libraries/chain/steem_evaluator.cpp
+++ b/libraries/chain/steem_evaluator.cpp
@@ -149,6 +149,9 @@ void account_update_evaluator::do_apply( const account_update_operation& o )
 {
    if( db().has_hardfork( STEEMIT_HARDFORK_0_1 ) ) FC_ASSERT( o.account != STEEMIT_TEMP_ACCOUNT, "cannot update temp account" );
 
+   if( db().is_producing() && o.posting ) // TODO: Add HF 15
+      o.posting->validate();
+
    const auto& account = db().get_account( o.account );
 
    if( o.owner )
@@ -158,9 +161,34 @@ void account_update_evaluator::do_apply( const account_update_operation& o )
          FC_ASSERT( db().head_block_time() - account.last_owner_update > STEEMIT_OWNER_UPDATE_LIMIT, "can only update owner authority once a minute" );
 #endif
 
+      if( db().is_producing() ) // TODO: Add HF 15
+      {
+         for( auto a: o.owner->account_auths )
+         {
+            db().get_account( a.first );
+         }
+      }
+
+
       db().update_owner_authority( account, *o.owner );
    }
 
+   if( o.active && db().is_producing() ) // TODO: Add HF 15
+   {
+      for( auto a: o.active->account_auths )
+      {
+         db().get_account( a.first );
+      }
+   }
+
+   if( o.posting && db().is_producing() ) // TODO: Add HF 15
+   {
+      for( auto a: o.posting->account_auths )
+      {
+         db().get_account( a.first );
+      }
+   }
+
    db().modify( account, [&]( account_object& acc )
    {
       if( o.active ) acc.active = *o.active;
diff --git a/tests/tests/operation_tests.cpp b/tests/tests/operation_tests.cpp
index dacb79197e..3596e88c87 100644
--- a/tests/tests/operation_tests.cpp
+++ b/tests/tests/operation_tests.cpp
@@ -177,6 +177,28 @@ BOOST_AUTO_TEST_CASE( account_update_validate )
    {
       BOOST_TEST_MESSAGE( "Testing: account_update_validate" );
 
+      ACTORS( (alice) )
+
+      account_update_operation op;
+      op.account = "alice";
+      op.posting = authority();
+      op.posting->weight_threshold = 1;
+      op.posting->add_authorities( "abcdefghijklmnopq", 1 );
+
+      try
+      {
+         op.validate();
+
+         signed_transaction tx;
+         tx.set_expiration( db.head_block_time() + STEEMIT_MAX_TIME_UNTIL_EXPIRATION );
+         tx.operations.push_back( op );
+         tx.sign( alice_private_key, db.get_chain_id() );
+         db.push_transaction( tx, 0 );
+
+         BOOST_FAIL( "An exception was not thrown for an invalid account name" );
+      }
+      catch( fc::assert_exception& ) {}
+
       validate_database();
    }
    FC_LOG_AND_RETHROW()
@@ -314,6 +336,19 @@ BOOST_AUTO_TEST_CASE( account_update_apply )
       tx.sign( new_private_key, db.get_chain_id() );
       STEEMIT_REQUIRE_THROW( db.push_transaction( tx, 0 ), fc::assert_exception )
       validate_database();
+
+
+      BOOST_TEST_MESSAGE( "--- Test failure when account authority does not exist" );
+      tx.clear();
+      op = account_update_operation();
+      op.account = "alice";
+      op.posting = authority();
+      op.posting->weight_threshold = 1;
+      op.posting->add_authorities( "dave", 1 );
+      tx.operations.push_back( op );
+      tx.sign( new_private_key, db.get_chain_id() );
+      STEEMIT_REQUIRE_THROW( db.push_transaction( tx, 0 ), fc::assert_exception );
+      validate_database();
    }
    FC_LOG_AND_RETHROW()
 }
@@ -781,7 +816,6 @@ BOOST_AUTO_TEST_CASE( vote_apply )
          new_cashout_time = db.head_block_time().sec_since_epoch() + STEEMIT_CASHOUT_WINDOW_SECONDS;
          int64_t regenerated_power = (STEEMIT_100_PERCENT * ( db.head_block_time() - db.get_account( "alice").last_vote_time ).to_seconds() ) / STEEMIT_VOTE_REGENERATION_SECONDS;
          int64_t used_power = ( db.get_account( "alice" ).voting_power + regenerated_power + max_vote_denom - 1 ) / max_vote_denom;
-         idump( (db.get_account( "alice" ).voting_power)(used_power) );
 
          comment_op.author = "sam";
          comment_op.permlink = "foo";
@@ -3555,6 +3589,8 @@ BOOST_AUTO_TEST_CASE( pow2_op )
 
       ACTORS( (bob) )
 
+      target = db.get_pow_summary_target();
+
       do
       {
          nonce++;