diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 0d2bd7a3576..a22f7addacc 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -66,6 +66,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/pg_database.h"
 #include "common/controldata_utils.h"
+#include "common/file_utils.h"
 #include "executor/instrument.h"
 #include "miscadmin.h"
 #include "pg_trace.h"
@@ -8292,6 +8293,19 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 
 			snprintf(fullpath, sizeof(fullpath), "pg_tblspc/%s", de->d_name);
 
+			/*
+			 * Skip anything that isn't a symlink/junction.  For testing only,
+			 * we sometimes use allow_in_place_tablespaces to create
+			 * directories directly under pg_tblspc, which would fail below.
+			 */
+#ifdef WIN32
+			if (!pgwin32_is_junction(fullpath))
+				continue;
+#else
+			if (get_dirent_type(fullpath, de, false, ERROR) != PGFILETYPE_LNK)
+				continue;
+#endif
+
 #if defined(HAVE_READLINK) || defined(WIN32)
 			rllen = readlink(fullpath, linkpath, sizeof(linkpath));
 			if (rllen < 0)