*** a/src/bin/pg_upgrade/server.c
--- b/src/bin/pg_upgrade/server.c
***************
*** 285,293 **** start_postmaster(ClusterInfo *cluster, bool throw_error)
  			   PQerrorMessage(conn));
  		if (conn)
  			PQfinish(conn);
! 		pg_fatal("could not connect to %s postmaster started with the command:\n"
! 				 "%s\n",
! 				 CLUSTER_NAME(cluster), cmd);
  	}
  	PQfinish(conn);
  
--- 285,297 ----
  			   PQerrorMessage(conn));
  		if (conn)
  			PQfinish(conn);
! 		if (cluster == &old_cluster)
! 			pg_fatal("could not connect to source postmaster started with the command:\n"
! 					 "%s\n", cmd);
! 		else
! 			pg_fatal("could not connect to target postmaster started with the command:\n"
! 					 "%s\n", cmd);
! 
  	}
  	PQfinish(conn);