diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index d843eee7e97..3ac47ce3e0e 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -222,7 +222,10 @@ dblink_get_conn(char *conname_or_str,
 			dblink_we_get_conn = WaitEventExtensionNew("DblinkGetConnect");
 
 		/* OK to make connection */
-		conn = libpqsrv_connect(connstr, dblink_we_get_conn);
+		conn = libpqsrv_connect_start(connstr);
+		PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
+							"received message via remote connection");
+		libpqsrv_connect_complete(conn, dblink_we_get_conn);
 
 		if (PQstatus(conn) == CONNECTION_BAD)
 		{
@@ -235,9 +238,6 @@ dblink_get_conn(char *conname_or_str,
 					 errdetail_internal("%s", msg)));
 		}
 
-		PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
-							"received message via remote connection");
-
 		dblink_security_check(conn, NULL, connstr);
 		if (PQclientEncoding(conn) != GetDatabaseEncoding())
 			PQsetClientEncoding(conn, GetDatabaseEncodingName());
@@ -321,7 +321,11 @@ dblink_connect(PG_FUNCTION_ARGS)
 	}
 
 	/* OK to make connection */
-	conn = libpqsrv_connect(connstr, dblink_we_connect);
+	conn = libpqsrv_connect_start(connstr);
+	if (conn != NULL)
+		PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
+							"received message via remote connection");
+	libpqsrv_connect_complete(conn, dblink_we_connect);
 
 	if (PQstatus(conn) == CONNECTION_BAD)
 	{
@@ -336,9 +340,6 @@ dblink_connect(PG_FUNCTION_ARGS)
 				 errdetail_internal("%s", msg)));
 	}
 
-	PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
-						"received message via remote connection");
-
 	/* check password actually used if not superuser */
 	dblink_security_check(conn, connname, connstr);
 
diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
index 3d2a8d0519d..c3a1c5f46ca 100644
--- a/contrib/postgres_fdw/connection.c
+++ b/contrib/postgres_fdw/connection.c
@@ -638,6 +638,7 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
 		const char **keywords;
 		const char **values;
 		char	   *appname;
+		PGconn	   *start_conn;
 
 		construct_connection_params(server, user, &keywords, &values, &appname);
 
@@ -646,9 +647,12 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
 			pgfdw_we_connect = WaitEventExtensionNew("PostgresFdwConnect");
 
 		/* OK to make connection */
-		conn = libpqsrv_connect_params(keywords, values,
-									   false,	/* expand_dbname */
-									   pgfdw_we_connect);
+		start_conn = libpqsrv_connect_params_start(keywords, values,
+												    /* expand_dbname = */ false);
+		PQsetNoticeReceiver(start_conn, libpqsrv_notice_receiver,
+							"received message via remote connection");
+		libpqsrv_connect_complete(start_conn, pgfdw_we_connect);
+		conn = start_conn;
 
 		if (!conn || PQstatus(conn) != CONNECTION_OK)
 			ereport(ERROR,
@@ -657,9 +661,6 @@ connect_pg_server(ForeignServer *server, UserMapping *user)
 							server->servername),
 					 errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
 
-		PQsetNoticeReceiver(conn, libpqsrv_notice_receiver,
-							"received message via remote connection");
-
 		/* Perform post-connection security checks. */
 		pgfdw_security_check(keywords, values, user, conn);
 
diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index 9f04c9ed25d..ebfd64bdf05 100644
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -223,9 +223,12 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 
 	conn = palloc0_object(WalReceiverConn);
 	conn->streamConn =
-		libpqsrv_connect_params(keys, vals,
-								 /* expand_dbname = */ true,
-								WAIT_EVENT_LIBPQWALRECEIVER_CONNECT);
+		libpqsrv_connect_params_start(keys, vals,
+									   /* expand_dbname = */ true);
+	PQsetNoticeReceiver(conn->streamConn, libpqsrv_notice_receiver,
+						"received message via replication");
+	libpqsrv_connect_complete(conn->streamConn,
+							  WAIT_EVENT_LIBPQWALRECEIVER_CONNECT);
 
 	if (options_val != NULL)
 		pfree(options_val);
@@ -245,9 +248,6 @@ libpqrcv_connect(const char *conninfo, bool replication, bool logical,
 				 errhint("Target server's authentication method must be changed, or set password_required=false in the subscription parameters.")));
 	}
 
-	PQsetNoticeReceiver(conn->streamConn, libpqsrv_notice_receiver,
-						"received message via replication");
-
 	/*
 	 * Set always-secure search path for the cases where the connection is
 	 * used to run SQL queries, so malicious users can't get control.
diff --git a/src/include/libpq/libpq-be-fe-helpers.h b/src/include/libpq/libpq-be-fe-helpers.h
index 85d8b63f019..cff68cd1c37 100644
--- a/src/include/libpq/libpq-be-fe-helpers.h
+++ b/src/include/libpq/libpq-be-fe-helpers.h
@@ -39,10 +39,28 @@
 
 
 static inline void libpqsrv_connect_prepare(void);
-static inline void libpqsrv_connect_internal(PGconn *conn, uint32 wait_event_info);
+static inline void libpqsrv_connect_complete(PGconn *conn, uint32 wait_event_info);
 static inline PGresult *libpqsrv_get_result_last(PGconn *conn, uint32 wait_event_info);
 static inline PGresult *libpqsrv_get_result(PGconn *conn, uint32 wait_event_info);
 
+/*
+ * Start a connection using PQconnectStart().
+ *
+ * The returned connection has not yet completed its startup sequence.  Callers
+ * may perform per-connection setup, such as installing a notice receiver,
+ * before calling libpqsrv_connect_complete().
+ *
+ * Callers must call libpqsrv_connect_complete(), even if this function returns
+ * NULL, because libpqsrv_connect_prepare() may already have reserved an
+ * external FD that must be released.
+ */
+static inline PGconn *
+libpqsrv_connect_start(const char *conninfo)
+{
+	libpqsrv_connect_prepare();
+
+	return PQconnectStart(conninfo);
+}
 
 /*
  * PQconnectdb() wrapper that reserves a file descriptor and processes
@@ -55,17 +73,30 @@ static inline PGresult *libpqsrv_get_result(PGconn *conn, uint32 wait_event_info
 static inline PGconn *
 libpqsrv_connect(const char *conninfo, uint32 wait_event_info)
 {
-	PGconn	   *conn = NULL;
+	PGconn	   *conn;
 
-	libpqsrv_connect_prepare();
+	conn = libpqsrv_connect_start(conninfo);
 
-	conn = PQconnectStart(conninfo);
-
-	libpqsrv_connect_internal(conn, wait_event_info);
+	libpqsrv_connect_complete(conn, wait_event_info);
 
 	return conn;
 }
 
+/*
+ * Start a connection using PQconnectStartParams().
+ *
+ * See libpqsrv_connect_start() for the resource-lifetime rules.
+ */
+static inline PGconn *
+libpqsrv_connect_params_start(const char *const *keywords,
+							  const char *const *values,
+							  int expand_dbname)
+{
+	libpqsrv_connect_prepare();
+
+	return PQconnectStartParams(keywords, values, expand_dbname);
+}
+
 /*
  * Like libpqsrv_connect(), except that this is a wrapper for
  * PQconnectdbParams().
@@ -76,13 +107,11 @@ libpqsrv_connect_params(const char *const *keywords,
 						int expand_dbname,
 						uint32 wait_event_info)
 {
-	PGconn	   *conn = NULL;
+	PGconn	   *conn;
 
-	libpqsrv_connect_prepare();
+	conn = libpqsrv_connect_params_start(keywords, values, expand_dbname);
 
-	conn = PQconnectStartParams(keywords, values, expand_dbname);
-
-	libpqsrv_connect_internal(conn, wait_event_info);
+	libpqsrv_connect_complete(conn, wait_event_info);
 
 	return conn;
 }
@@ -90,8 +119,9 @@ libpqsrv_connect_params(const char *const *keywords,
 /*
  * PQfinish() wrapper that additionally releases the reserved file descriptor.
  *
- * It is allowed to call this with a NULL pgconn iff NULL was returned by
- * libpqsrv_connect*.
+ * It is allowed to call this with NULL only when the external FD reservation
+ * has already been released, for example after calling
+ * libpqsrv_connect_complete() with a NULL connection.
  */
 static inline void
 libpqsrv_disconnect(PGconn *conn)
@@ -101,7 +131,7 @@ libpqsrv_disconnect(PGconn *conn)
 	 * already released it). This rule makes it easier to write PG_CATCH()
 	 * handlers for this facility's users.
 	 *
-	 * See also libpqsrv_connect_internal().
+	 * See also libpqsrv_connect_complete().
 	 */
 	if (conn == NULL)
 		return;
@@ -111,7 +141,7 @@ libpqsrv_disconnect(PGconn *conn)
 }
 
 
-/* internal helper functions follow */
+/* lower-level connection helper functions follow */
 
 
 /*
@@ -144,10 +174,11 @@ libpqsrv_connect_prepare(void)
 }
 
 /*
- * Helper function for all connection establishment functions.
+ * Complete a connection started by libpqsrv_connect_start() or
+ * libpqsrv_connect_params_start().
  */
 static inline void
-libpqsrv_connect_internal(PGconn *conn, uint32 wait_event_info)
+libpqsrv_connect_complete(PGconn *conn, uint32 wait_event_info)
 {
 	/*
 	 * With conn == NULL libpqsrv_disconnect() wouldn't release the FD. So do