KCFinder browser shows empty pop-up window. How to debug?

Question

I've just upgrade a site, which as far as I'm aware was working fine, from CiviCRM 4.6.x to 4.7.8. Only now the file/image browser and file upload facility within the CKEditor (which I understand is provided by KCFinder, is displaying nothing in the file/image browser and won't let me upload anything. Don't know if this is a bug in the 4.7.8 release for Wordpress. I've never come across this issue before in CiviCRM, on dozens of different sites. I've read that KCFinder is fussy about paths and permissions. Any pointers about how to fix this very welcome.

Update: from the error log I see that each time I open up the KCFinder browse window I get a pattern of notices and warnings, ending with a fatal error:

PHP Notice: Undefined variable: output in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php on line 403, referer: http://account.co.uk/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fevent%2Fadd&reset=1&action=add

PHP Warning: exec() has been disabled for security reasons in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php on line 403, referer: http://account.co.uk/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fevent%2Fadd&reset=1&action=add

PHP Notice: Undefined variable: output in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php on line 404, referer: http://account.co.uk/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fevent%2Fadd&reset=1&action=add

PHP Warning: implode(): Invalid arguments passed in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php on line 404, referer: http://account.co.uk/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fevent%2Fadd&reset=1&action=add

PHP Fatal error: Uncaught exception 'Exception' with message 'Failed to locate civicrm.settings.php. Please boot with settingsFile, search, or CIVICRM_SETTINGS; or normalize your directory structure.' in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php:125\nStack trace:\n#0 /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php(413): Civi\Cv\Bootstrap->boot()\n#1 /home/account/sites/default/wp-content/plugins/civicrm/civicrm/packages/kcfinder/integration/civicrm.php(45): require_once('/home/account/si...')\n#2 /home/account/sites/default/wp-content/plugins/civicrm/civicrm/packages/kcfinder/integration/civicrm.php(140): checkAuthentication()\n#3 /home/account/sites/default/wp-content/plugins/civicrm/civicrm/packages/kcfinder/core/bootstrap.php(39): require('/home/account/si...')\n#4 /home/account/sites/default/wp-content/plugins/civicrm/civicrm/packages/kcfinder/browse.php(15): require('/home/account/si...')\n#5 {main}\n thrown in /home/account/sites/default/wp-content/plugins/civicrm/civicrm/civicrm.config.php on line 125, referer: http://account.co.uk/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fevent%2Fadd&reset=1&action=add

I've got 4.6.x sites running on the exact same server set-up with no issues. This is the first site with 4.7.x on this server.

Answer 1

There used to be a requirement that the URLs that Andrei referred to above could not contain symbolic links. I don't know if that is still the case, but make sure that all directories in that path are true directories and not symbolic links.

Answer 2

I don't think there's an intentional change in system requirements. However, looking at civicrm.config.php, I can see it's undergone recent changes. It looks like you're having trouble because your PHP configuration doesn't allow running the "exec" command. That's often done for security - but if you can change your configuration to allow it, I think you'll be better off.

If not, maybe change line 401 in civicrm.config.php to read:

if (true) {

to force it to use the alternate method of finding your search directory?

Please try either changing that line or your PHP configuration to allow "exec" and let us know if it solved the problem for you!