*** a/src/backend/replication/syncrep.c
--- b/src/backend/replication/syncrep.c
***************
*** 376,385 **** SyncRepReleaseWaiters(void)
  	/*
  	 * If this WALSender is serving a standby that is not on the list of
  	 * potential standbys then we have nothing to do. If we are still starting
! 	 * up or still running base backup, then leave quickly also.
  	 */
  	if (MyWalSnd->sync_standby_priority == 0 ||
! 		MyWalSnd->state < WALSNDSTATE_STREAMING)
  		return;
  
  	/*
--- 376,387 ----
  	/*
  	 * If this WALSender is serving a standby that is not on the list of
  	 * potential standbys then we have nothing to do. If we are still starting
! 	 * up, still running base backup or the current flush position is still
! 	 * invalid, then leave quickly also.
  	 */
  	if (MyWalSnd->sync_standby_priority == 0 ||
! 		MyWalSnd->state < WALSNDSTATE_STREAMING ||
! 		XLogRecPtrIsInvalid(MyWalSnd->flush))
  		return;
  
  	/*
***************
*** 399,405 **** SyncRepReleaseWaiters(void)
  			walsnd->state == WALSNDSTATE_STREAMING &&
  			walsnd->sync_standby_priority > 0 &&
  			(priority == 0 ||
! 			 priority > walsnd->sync_standby_priority))
  		{
  			priority = walsnd->sync_standby_priority;
  			syncWalSnd = walsnd;
--- 401,408 ----
  			walsnd->state == WALSNDSTATE_STREAMING &&
  			walsnd->sync_standby_priority > 0 &&
  			(priority == 0 ||
! 			 priority > walsnd->sync_standby_priority) &&
! 			!XLogRecPtrIsInvalid(walsnd->flush))
  		{
  			priority = walsnd->sync_standby_priority;
  			syncWalSnd = walsnd;
*** a/src/backend/replication/walreceiver.c
--- b/src/backend/replication/walreceiver.c
***************
*** 281,286 **** WalReceiverMain(void)
--- 281,291 ----
  	walrcv_connect(conninfo, startpoint);
  	DisableWalRcvImmediateExit();
  
+ 	/* Initialize LogstreamResult, reply_message and feedback_message */
+ 	LogstreamResult.Write = LogstreamResult.Flush = GetXLogReplayRecPtr(NULL);
+ 	MemSet(&reply_message, 0, sizeof(reply_message));
+ 	MemSet(&feedback_message, 0, sizeof(feedback_message));
+ 
  	/* Loop until end-of-streaming or error */
  	for (;;)
  	{
*** a/src/backend/replication/walsender.c
--- b/src/backend/replication/walsender.c
***************
*** 1510,1521 **** pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
  
  		if (walsnd->pid != 0)
  		{
! 			sync_priority[i] = walsnd->sync_standby_priority;
  
  			if (walsnd->state == WALSNDSTATE_STREAMING &&
  				walsnd->sync_standby_priority > 0 &&
  				(priority == 0 ||
! 				 priority > walsnd->sync_standby_priority))
  			{
  				priority = walsnd->sync_standby_priority;
  				sync_standby = i;
--- 1510,1528 ----
  
  		if (walsnd->pid != 0)
  		{
! 			/*
! 			 * Treat the standby like pg_basebackup background process
! 			 * which always returns an invalid flush location, as an
! 			 * asynchronous standby.
! 			 */
! 			sync_priority[i] = XLogRecPtrIsInvalid(walsnd->flush) ?
! 				0 : walsnd->sync_standby_priority;
  
  			if (walsnd->state == WALSNDSTATE_STREAMING &&
  				walsnd->sync_standby_priority > 0 &&
  				(priority == 0 ||
! 				 priority > walsnd->sync_standby_priority) &&
! 				!XLogRecPtrIsInvalid(walsnd->flush))
  			{
  				priority = walsnd->sync_standby_priority;
  				sync_standby = i;
*** a/src/bin/pg_basebackup/receivelog.c
--- b/src/bin/pg_basebackup/receivelog.c
***************
*** 264,270 **** localTimestampDifferenceExceeds(TimestampTz start_time,
   * Note: The log position *must* be at a log segment start!
   */
  bool
! ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline, char *sysidentifier, char *basedir, stream_stop_callback stream_stop, int standby_message_timeout, bool rename_partial)
  {
  	char		query[128];
  	char		current_walfile_name[MAXPGPATH];
--- 264,273 ----
   * Note: The log position *must* be at a log segment start!
   */
  bool
! ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
! 				  char *sysidentifier, char *basedir,
! 				  stream_stop_callback stream_stop,
! 				  int standby_message_timeout, bool rename_partial)
  {
  	char		query[128];
  	char		current_walfile_name[MAXPGPATH];
***************
*** 359,365 **** ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline, char *sysi
  			char		replybuf[sizeof(StandbyReplyMessage) + 1];
  			StandbyReplyMessage *replymsg = (StandbyReplyMessage *) (replybuf + 1);
  
! 			replymsg->write = InvalidXLogRecPtr;
  			replymsg->flush = InvalidXLogRecPtr;
  			replymsg->apply = InvalidXLogRecPtr;
  			replymsg->sendTime = now;
--- 362,368 ----
  			char		replybuf[sizeof(StandbyReplyMessage) + 1];
  			StandbyReplyMessage *replymsg = (StandbyReplyMessage *) (replybuf + 1);
  
! 			replymsg->write = blockpos;
  			replymsg->flush = InvalidXLogRecPtr;
  			replymsg->apply = InvalidXLogRecPtr;
  			replymsg->sendTime = now;