diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 198ae1107e..560ea945ae 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -210,6 +210,7 @@
 		<li>[Fix] Do not display links to user/post search if search is disabled. (Bug #50685 - Patch by HardStyle)</li>
 		<li>[Fix] Fix icon alignment for forums with large descriptions in subsilver2. (Bug #50445)</li>
 		<li>[Fix] Correctly display underlined links placed in last line in viewtopic. (Bug #14811 - Patch by primehalo)</li>
+		<li>[Fix] Only check whether forum image exists if forum image is specified. (Bug #51905)</li>
 		<li>[Change] submit_post() now accepts force_approved_state key passed to $data to indicate new posts being approved (true) or unapproved (false).</li>
 		<li>[Change] Change the data format of the default file ACM to be more secure from tampering and have better performance.</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/acp/acp_forums.php b/phpBB/includes/acp/acp_forums.php
index c734572b05..62ccbdb68e 100644
--- a/phpBB/includes/acp/acp_forums.php
+++ b/phpBB/includes/acp/acp_forums.php
@@ -907,7 +907,7 @@ class acp_forums
 			array('lang' => 'FORUM_TOPICS_PAGE', 'value' => $forum_data['forum_topics_per_page'], 'column_type' => 'TINT:0'),
 		);
 
-		if (!file_exists($phpbb_root_path . $forum_data['forum_image']))
+		if (!empty($forum_data['forum_image']) && !file_exists($phpbb_root_path . $forum_data['forum_image']))
 		{
 			$errors[] = $user->lang['FORUM_IMAGE_NO_EXIST'];
 		}