diff --git a/phpBB/install/startup.php b/phpBB/install/startup.php
index 4e012216a6..71f5744678 100644
--- a/phpBB/install/startup.php
+++ b/phpBB/install/startup.php
@@ -159,9 +159,9 @@ function installer_shutdown_function($display_errors)
 		installer_class_loader($phpbb_root_path, $phpEx);
 		$supported_error_levels = E_ALL & ~E_NOTICE & ~E_DEPRECATED & ~E_USER_DEPRECATED;
 
-		$cache = new \phpbb\cache\driver\file(__DIR__ . '/../cache/installer');
+		$cache = new \phpbb\cache\driver\file(__DIR__ . '/../cache/installer/');
 		$filesystem = new \phpbb\filesystem\filesystem();
-		if (strpos($error['file'], $filesystem->realpath($cache->cache_dir)) !== false)
+		if (strpos($error['file'], $filesystem->realpath($cache->cache_dir)) !== false && is_writable($cache->cache_dir))
 		{
 			$file_age = @filemtime($error['file']);
 
diff --git a/phpBB/phpbb/cache/driver/file.php b/phpBB/phpbb/cache/driver/file.php
index 2dc9f350c2..0a4f0ae31e 100644
--- a/phpBB/phpbb/cache/driver/file.php
+++ b/phpBB/phpbb/cache/driver/file.php
@@ -37,9 +37,9 @@ class file extends \phpbb\cache\driver\base
 		$this->cache_dir = !is_null($cache_dir) ? $cache_dir : $phpbb_container->getParameter('core.cache_dir');
 		$this->filesystem = new \phpbb\filesystem\filesystem();
 
-		if (!is_dir($this->cache_dir))
+		if ($this->filesystem->is_writable(dirname($this->cache_dir)) && !is_dir($this->cache_dir))
 		{
-			@mkdir($this->cache_dir, 0777, true);
+			mkdir($this->cache_dir, 0777, true);
 		}
 	}
 
diff --git a/phpBB/phpbb/filesystem/filesystem.php b/phpBB/phpbb/filesystem/filesystem.php
index 6d34d990e2..39e95acc98 100644
--- a/phpBB/phpbb/filesystem/filesystem.php
+++ b/phpBB/phpbb/filesystem/filesystem.php
@@ -380,13 +380,13 @@ class filesystem implements filesystem_interface
 					$file_gid = @filegroup($current_file);
 
 					// Change owner
-					if ($file_uid !== $this->chmod_info['common_owner'])
+					if (is_writable($file) && $file_uid !== $this->chmod_info['common_owner'])
 					{
 						$this->chown($current_file, $this->chmod_info['common_owner'], $recursive);
 					}
 
 					// Change group
-					if ($file_gid !== $this->chmod_info['common_group'])
+					if (is_writable($file) && $file_gid !== $this->chmod_info['common_group'])
 					{
 						$this->chgrp($current_file, $this->chmod_info['common_group'], $recursive);
 					}
diff --git a/phpBB/phpbb/install/module/requirements/task/check_filesystem.php b/phpBB/phpbb/install/module/requirements/task/check_filesystem.php
index cac0c541cf..f08b7b960d 100644
--- a/phpBB/phpbb/install/module/requirements/task/check_filesystem.php
+++ b/phpBB/phpbb/install/module/requirements/task/check_filesystem.php
@@ -217,6 +217,7 @@ class check_filesystem extends \phpbb\install\task_base
 			catch (\phpbb\filesystem\exception\filesystem_exception $e)
 			{
 				// Do nothing
+				$this->response->add_warning_message($e->getMessage(), $e->get_filename());
 			}
 		}
 
@@ -232,6 +233,7 @@ class check_filesystem extends \phpbb\install\task_base
 			}
 			catch (\phpbb\filesystem\exception\filesystem_exception $e)
 			{
+				$this->response->add_warning_message($e->getMessage(), $e->get_filename());
 				// Do nothing
 			}
 		}