Fatal error: Uncaught exception 'UnexpectedValueException' with message 'RecursiveDirectoryIterator::__construct(/var/www/clients/client2/web18/web/custom/backup/modules) [<a href='recursivedirectoryiterator.--construct'>recursivedirectoryiterator.--construct</a>]: failed to open dir: Too many open files' in /var/www/clients/client2/web18/web/include/utils/php_zip_utils.php:79 Stack trace: #0 [internal function]: RecursiveDirectoryIterator->__construct('/var/www/client...') #1 /var/www/clients/client2/web18/web/include/utils/php_zip_utils.php(79): RecursiveDirectoryIterator->getChildren() #2 /var/www/clients/client2/web18/web/modules/Administration/DiagnosticRun.php(565): zip_dir('custom', 'cache/diagnosti...') #3 /var/www/clients/client2/web18/web/modules/Administration/DiagnosticRun.php(782): executecustom_dir() #4 /var/www/clients/client2/web18/web/include/MVC/View/SugarView.php(665): require_once('/var/www/client...') #5 /var/www/clients/client2/web18/web/include/MVC/View/views/view.classic.php(58): SugarView->include in /var/www/clients/client2/web18/web/include/utils/php_zip_utils.php on line 79

I get this error when trying to do diagnostics.

Recently upgraded to ver 6.3. Linux distro.