--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -3721,13 +3721,21 @@
 			break;
 
 			/*
-			 * In an implicit transaction block, commit, but issue a warning
-			 * because there was no explicit BEGIN before this.
+			 * We are in an implicit transaction block.  If AND CHAIN was
+			 * specified, we abort this transaction; otherwise commit, but
+			 * issue a warning because there was no explicit BEGIN before this.
 			 */
 		case TBLOCK_IMPLICIT_INPROGRESS:
-			ereport(WARNING,
-					(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
-					 errmsg("there is no transaction in progress")));
+			if (chain)
+				ereport(ERROR,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+				/* translator: %s represents an SQL statement name */
+						 errmsg("%s can only be used in transaction blocks",
+								"COMMIT AND CHAIN")));
+			else
+				ereport(WARNING,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+						 errmsg("there is no transaction in progress")));
 			s->blockState = TBLOCK_END;
 			result = true;
 			break;
@@ -3789,15 +3797,26 @@
 			break;
 
 			/*
-			 * The user issued COMMIT when not inside a transaction.  Issue a
-			 * WARNING, staying in TBLOCK_STARTED state.  The upcoming call to
+			 * The user issued COMMIT when not inside a transaction.  For
+			 * COMMIT without transaction chaining, we just issue a WARNING,
+			 * staying in TBLOCK_STARTED state.  The upcoming call to
 			 * CommitTransactionCommand() will then close the transaction and
 			 * put us back into the default state.
+			 *
+			 * We disallow transaction chaining outside an explicit transaction
+			 * block, so issue an ERROR if the user told us to do that.
 			 */
 		case TBLOCK_STARTED:
-			ereport(WARNING,
-					(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
-					 errmsg("there is no transaction in progress")));
+			if (chain)
+				ereport(ERROR,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+				/* translator: %s represents an SQL statement name */
+						 errmsg("%s can only be used in transaction blocks",
+								"COMMIT AND CHAIN")));
+			else
+				ereport(WARNING,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+						 errmsg("there is no transaction in progress")));
 			result = true;
 			break;
 
@@ -3899,10 +3918,13 @@
 			break;
 
 			/*
-			 * The user issued ABORT when not inside a transaction. Issue a
-			 * WARNING and go to abort state.  The upcoming call to
-			 * CommitTransactionCommand() will then put us back into the
-			 * default state.
+			 * The user issued ABORT when not inside a transaction.  For
+			 * ROLLBACK without transaction chaining, issue a WARNING and go
+			 * to abort state.  The upcoming call to CommitTransactionCommand()
+			 * will then put us back into the default state.
+			 *
+			 * We disallow transaction chaining outside an explicit transaction
+			 * block, so issue an ERROR if the user told us to do that.
 			 *
 			 * We do the same thing with ABORT inside an implicit transaction,
 			 * although in this case we might be rolling back actual database
@@ -3911,9 +3933,16 @@
 			 */
 		case TBLOCK_STARTED:
 		case TBLOCK_IMPLICIT_INPROGRESS:
-			ereport(WARNING,
-					(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
-					 errmsg("there is no transaction in progress")));
+			if (chain)
+				ereport(ERROR,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+				/* translator: %s represents an SQL statement name */
+						 errmsg("%s can only be used in transaction blocks",
+								"ROLLBACK AND CHAIN")));
+			else
+				ereport(WARNING,
+						(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
+						 errmsg("there is no transaction in progress")));
 			s->blockState = TBLOCK_ABORT_PENDING;
 			break;
 
--- a/src/test/regress/expected/transactions.out
+++ b/src/test/regress/expected/transactions.out
@@ -839,14 +839,87 @@
 (1 row)
 
 ROLLBACK;
+-- transaction chaining should not be used outside a transaction block
+COMMIT AND CHAIN;  -- error
+ERROR:  COMMIT AND CHAIN can only be used in transaction blocks
+ROLLBACK AND CHAIN;  -- error
+ERROR:  ROLLBACK AND CHAIN can only be used in transaction blocks
+-- transaction chaining in an implicit transaction block should also not be used
+SET TRANSACTION READ WRITE\; COMMIT AND CHAIN;  -- error
+ERROR:  COMMIT AND CHAIN can only be used in transaction blocks
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ on
+(1 row)
+
+SET TRANSACTION READ WRITE\; ROLLBACK AND CHAIN;  -- error
+ERROR:  ROLLBACK AND CHAIN can only be used in transaction blocks
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ on
+(1 row)
+
+-- a few more tests for implicit transaction chaining
+SET default_transaction_read_only = off;
+-- COMMIT/ROLLBACK ~ COMMIT/ROLLBACK AND CHAIN
+INSERT INTO abc VALUES (7)\; COMMIT\; INSERT INTO abc VALUES (8)\; COMMIT AND CHAIN;  -- 7 ok, 8 fail
+WARNING:  there is no transaction in progress
+ERROR:  COMMIT AND CHAIN can only be used in transaction blocks
+INSERT INTO abc VALUES (9)\; ROLLBACK\; INSERT INTO abc VALUES (10)\; ROLLBACK AND CHAIN;  -- 9 fail, 10 fail
+WARNING:  there is no transaction in progress
+ERROR:  ROLLBACK AND CHAIN can only be used in transaction blocks
+-- COMMIT/ROLLBACK AND CHAIN ~ COMMIT/ROLLBACK
+INSERT INTO abc VALUES (11)\; COMMIT AND CHAIN\; INSERT INTO abc VALUES (12)\; COMMIT;  -- 11 fail, 12 fail
+ERROR:  COMMIT AND CHAIN can only be used in transaction blocks
+INSERT INTO abc VALUES (13)\; ROLLBACK AND CHAIN\; INSERT INTO abc VALUES (14)\; ROLLBACK;  -- 13 fail, 14 fail
+ERROR:  ROLLBACK AND CHAIN can only be used in transaction blocks
+-- START TRANSACTION ~ COMMIT/ROLLBACK AND CHAIN
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (15)\; COMMIT AND CHAIN;  -- 15 ok
+SHOW transaction_isolation;  -- transaction is active at this point
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (16)\; ROLLBACK AND CHAIN;  -- 16 fail
+SHOW transaction_isolation;  -- transaction is active at this point
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+ROLLBACK;
+-- START TRANSACTION ~ COMMIT/ROLLBACK ~ COMMIT/ROLLBACK AND CHAIN
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (17)\; COMMIT\; INSERT INTO abc VALUES (18)\; COMMIT AND CHAIN;  -- 17 ok, 18 fail
+ERROR:  COMMIT AND CHAIN can only be used in transaction blocks
+SHOW transaction_isolation;  -- out of transaction block
+ transaction_isolation 
+-----------------------
+ read committed
+(1 row)
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (19)\; ROLLBACK\; INSERT INTO abc VALUES (20)\; ROLLBACK AND CHAIN;  -- 19 fail, 20 fail
+ERROR:  ROLLBACK AND CHAIN can only be used in transaction blocks
+SHOW transaction_isolation;  -- out of transaction block
+ transaction_isolation 
+-----------------------
+ read committed
+(1 row)
+
 SELECT * FROM abc ORDER BY 1;
- a 
----
- 1
- 2
- 4
- 5
-(4 rows)
+ a  
+----
+  1
+  2
+  4
+  5
+  7
+ 15
+ 17
+(7 rows)
 
 RESET default_transaction_read_only;
 DROP TABLE abc;
--- a/src/test/regress/sql/transactions.sql
+++ b/src/test/regress/sql/transactions.sql
@@ -475,6 +475,44 @@
 SHOW transaction_deferrable;
 ROLLBACK;
 
+-- transaction chaining should not be used outside a transaction block
+COMMIT AND CHAIN;  -- error
+ROLLBACK AND CHAIN;  -- error
+
+-- transaction chaining in an implicit transaction block should also not be used
+SET TRANSACTION READ WRITE\; COMMIT AND CHAIN;  -- error
+SHOW transaction_read_only;
+
+SET TRANSACTION READ WRITE\; ROLLBACK AND CHAIN;  -- error
+SHOW transaction_read_only;
+
+-- a few more tests for implicit transaction chaining
+SET default_transaction_read_only = off;
+
+-- COMMIT/ROLLBACK ~ COMMIT/ROLLBACK AND CHAIN
+INSERT INTO abc VALUES (7)\; COMMIT\; INSERT INTO abc VALUES (8)\; COMMIT AND CHAIN;  -- 7 ok, 8 fail
+INSERT INTO abc VALUES (9)\; ROLLBACK\; INSERT INTO abc VALUES (10)\; ROLLBACK AND CHAIN;  -- 9 fail, 10 fail
+
+-- COMMIT/ROLLBACK AND CHAIN ~ COMMIT/ROLLBACK
+INSERT INTO abc VALUES (11)\; COMMIT AND CHAIN\; INSERT INTO abc VALUES (12)\; COMMIT;  -- 11 fail, 12 fail
+INSERT INTO abc VALUES (13)\; ROLLBACK AND CHAIN\; INSERT INTO abc VALUES (14)\; ROLLBACK;  -- 13 fail, 14 fail
+
+-- START TRANSACTION ~ COMMIT/ROLLBACK AND CHAIN
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (15)\; COMMIT AND CHAIN;  -- 15 ok
+SHOW transaction_isolation;  -- transaction is active at this point
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (16)\; ROLLBACK AND CHAIN;  -- 16 fail
+SHOW transaction_isolation;  -- transaction is active at this point
+ROLLBACK;
+
+-- START TRANSACTION ~ COMMIT/ROLLBACK ~ COMMIT/ROLLBACK AND CHAIN
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (17)\; COMMIT\; INSERT INTO abc VALUES (18)\; COMMIT AND CHAIN;  -- 17 ok, 18 fail
+SHOW transaction_isolation;  -- out of transaction block
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ\; INSERT INTO abc VALUES (19)\; ROLLBACK\; INSERT INTO abc VALUES (20)\; ROLLBACK AND CHAIN;  -- 19 fail, 20 fail
+SHOW transaction_isolation;  -- out of transaction block
+
 SELECT * FROM abc ORDER BY 1;
 
 RESET default_transaction_read_only;