diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 266ea2a80a..15ec8cb4fc 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -157,6 +157,7 @@
 		<li>[Fix] Force full date for PMs print-view (Patch by nickvergessen)</li>
 		<li>[Fix] Fix &quot;Always show a scrollbar for short pages&quot; for IE8 and Firefox 3.5 (Bug #47865 - Patch by stokerpiller)</li>
 		<li>[Fix] Do not allow setting group as default group for pending user (Bug #45675 - Patch by nickvergessen)</li>
+		<li>[Fix] Fail gracefully if store folder is not writable during update. (Bugs #46615, #46945)</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] Add index on log_time to the log table to prevent slowdown on boards with many log entries. (Bug #44665 - Patch by bantu)</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/functions_compress.php b/phpBB/includes/functions_compress.php
index 881e1ba5cc..590daabf1d 100644
--- a/phpBB/includes/functions_compress.php
+++ b/phpBB/includes/functions_compress.php
@@ -155,7 +155,12 @@ class compress_zip extends compress
 	*/
 	function compress_zip($mode, $file)
 	{
-		return $this->fp = @fopen($file, $mode . 'b');
+		$this->fp = @fopen($file, $mode . 'b');
+
+		if (!$this->fp)
+		{
+			trigger_error('Unable to open file ' . $file . ' [' . $mode . 'b]');
+		}
 	}
 
 	/**
diff --git a/phpBB/install/install_update.php b/phpBB/install/install_update.php
index 388e217133..ccbad07e5b 100644
--- a/phpBB/install/install_update.php
+++ b/phpBB/install/install_update.php
@@ -915,6 +915,11 @@ class install_update extends module
 				// Now init the connection
 				if ($update_mode == 'download')
 				{
+					if (function_exists('phpbb_is_writable') && !phpbb_is_writable($phpbb_root_path . 'store/'))
+					{
+						trigger_error(sprintf($user->lang['DIRECTORY_NOT_WRITABLE'], $phpbb_root_path . 'store/'), E_USER_ERROR);
+					}
+
 					if ($use_method == '.zip')
 					{
 						$compress = new compress_zip('w', $phpbb_root_path . 'store/' . $archive_filename . $use_method);