diff --git a/src/backend/replication/logical/proto.c b/src/backend/replication/logical/proto.c
index f308713275..a038f80dbd 100644
--- a/src/backend/replication/logical/proto.c
+++ b/src/backend/replication/logical/proto.c
@@ -1213,9 +1213,11 @@ logicalrep_read_stream_abort(StringInfo in,
 /*
  * Get string representing LogicalRepMsgType.
  */
-char *
+const char *
 logicalrep_message_type(LogicalRepMsgType action)
 {
+	char	*err_unknown;
+
 	switch (action)
 	{
 		case LOGICAL_REP_MSG_BEGIN:
@@ -1258,7 +1260,12 @@ logicalrep_message_type(LogicalRepMsgType action)
 			return "STREAM PREPARE";
 	}
 
-	elog(ERROR, "invalid logical replication message type \"%c\"", action);
+	/*
+	 * This function is called to provide context in the error raised when
+	 * applying a logical message. So we can't throw an error here. Return an
+	 * unknown indicator value so that the original error is still reported.
+	 */
+	err_unknown = psprintf("??? (%d)", action);
 
-	return NULL;				/* keep compiler quiet */
+	return err_unknown;
 }
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index dd353fd1cb..cb6659fc61 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -3367,7 +3367,7 @@ apply_dispatch(StringInfo s)
 		default:
 			ereport(ERROR,
 					(errcode(ERRCODE_PROTOCOL_VIOLATION),
-					 errmsg("invalid logical replication message type \"%c\"", action)));
+					 errmsg("invalid logical replication message type \"??? (%d)\"", action)));
 	}
 
 	/* Reset the current command */
diff --git a/src/include/replication/logicalproto.h b/src/include/replication/logicalproto.h
index 0ea2df5088..c5be981eae 100644
--- a/src/include/replication/logicalproto.h
+++ b/src/include/replication/logicalproto.h
@@ -269,6 +269,6 @@ extern void logicalrep_write_stream_abort(StringInfo out, TransactionId xid,
 extern void logicalrep_read_stream_abort(StringInfo in,
 										 LogicalRepStreamAbortData *abort_data,
 										 bool read_abort_info);
-extern char *logicalrep_message_type(LogicalRepMsgType action);
+extern const char *logicalrep_message_type(LogicalRepMsgType action);
 
 #endif							/* LOGICAL_PROTO_H */