When trying to open File Manager in CCP, most of the frames get loaded, but after several seconds the following error is displayed:
Unable to connect to backend
In some cases you may get these errors directly in the browser or in PHP error log:
PHP Notice: Undefined index: culture in C:\Program Files (x86)\SWsoft\PEM\sysvhosts\elFinder\index.php on line 63 PHP Notice: Undefined offset: 0 in C:\Program Files (x86)\SWsoft\PEM\sysvhosts\elFinder\index.php on line 74
The issue is caused by outdated PHP version, e.g. 5.2.X, which has been EOL-ed since 6 Jan 2011.
Windows Webfilemanager uses several PHP methods, introduced only since version 5.3 (see POA 5.5 New Windows File Manager requirements).
Verify that PHP version on the Webfilemanager server is 5.3 or newer.
If you see that it is not, e.g
C:\Users\Administrator>php-cgi -v PHP 5.2.17 (cgi-fcgi) (built: Jan 6 2011 17:28:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2010 Zend Technologies with the ionCube PHP Loader v3.1.32, Copyright (c) 2002-2007, by ionCube Ltd
update PHP version to 5.3.