patch 8.0.0037
Problem:    Get E924 when switching tabs. ()
Solution:   Use win_valid_any_tab() instead of win_valid(). (Martin Vuille,
            closes #1167, closes #1171)
diff --git a/src/quickfix.c b/src/quickfix.c
index 9139663..5bd1257 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -2266,7 +2266,7 @@
 
 	    ok = buflist_getfile(qf_ptr->qf_fnum,
 			    (linenr_T)1, GETF_SETMARK | GETF_SWITCH, forceit);
-	    if (qi != &ql_info && !win_valid(oldwin))
+	    if (qi != &ql_info && !win_valid_any_tab(oldwin))
 	    {
 		EMSG(_("E924: Current window was closed"));
 		is_abort = TRUE;