From f1710b57bc62a2ce99e5b0534ad6b9e4497cd25c Mon Sep 17 00:00:00 2001
From: tgrant <tom.grant760@gmail.com>
Date: Sun, 27 Sep 2020 12:50:08 +0100
Subject: [PATCH] Fix null displayname crash as described in #21885

Signed-off-by: tgrant <tom.grant760@gmail.com>
---
 lib/private/Group/Database.php | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/private/Group/Database.php b/lib/private/Group/Database.php
index 29fcb503b100b..cc8ea2fb52b81 100644
--- a/lib/private/Group/Database.php
+++ b/lib/private/Group/Database.php
@@ -458,7 +458,11 @@ public function countDisabledInGroup(string $gid): int {
 
 	public function getDisplayName(string $gid): string {
 		if (isset($this->groupCache[$gid])) {
-			return $this->groupCache[$gid]['displayname'];
+                        $displayName = $this->groupCache[$gid]['displayname'];
+
+                        if (isset($displayName) && trim($displayName) !== '') {
+                                return $displayName;
+                        }
 		}
 
 		$this->fixDI();