Hey @direktorobi, It looks like error text didn’t come through in your message, so I can’t see what PHP is actually complaining about. Could you paste the exact error from your PHP error log (or wp-content/debug.log)?
A white screen on “Scan files” is almost always PHP hitting a hard limit while scanning the whole uploads folder in one request, which is what the free version does. Since you’ve already raised memory, max execution time, and max input time, a few things that help narrow it down:
- Before trying “Scan files” again, enable WordPress debug logging so we capture the real error. In
wp-config.php:
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
Then check wp-content/debug.log for the last error at the time of the crash, and paste it here.
- Roughly how many files/folders are in
wp-content/uploads? The free version loads and scans everything at once, so very large libraries can exhaust memory or time regardless of how high you set the limits (some hosts cap these at the server/php-fpm level, so an ini_set from the plugin won’t stick).
- If your PHP limits are being overridden by the host, the values in Tools > Site Health > Info > Server will show what’s actually in effect, not what you set.
Hope it helps.
Erol
- Sure! I anonymized the url.
This is from our website’s server logs:
PHP Fatal error: ob_end_flush(): Cannot use output buffering in output buffering display handlers in /var/www/vhosts/example.com/httpdocs/wp-includes/functions.php on line 5581
Stack trace: 0 /var/www/vhosts/example.com/httpdocs/wp-includes/functions.php(5581): ob_end_flush() 1 /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php(353): wp_ob_end_flush_all() 2 /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php(377): WP_Hook->apply_filters() 3 /var/www/vhosts/example.com/httpdocs/wp-includes/plugin.php(523): WP_Hook->do_action() 4 /var/www/vhosts/example.com/httpdocs/wp-includes/load.php(1308): do_action() 5 [internal function]: shutdown_action_hook() 6 {main}
Referer:
https://www.example.com/wp-admin/upload.php?page=media-sync-page
This is from debug.log:
[22-Sep-2026 22:03:25 UTC] PHP Fatal error: ob_end_flush(): Cannot use output buffering in output buffering display handlers in /var/www/vhosts/example.com/httpdocs/wp-includes/functions.php on line 5581
Stack trace: 0 /var/www/vhosts/example.com/httpdocs/wp-includes/functions.php(5581): ob_end_flush() 1 /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php(353): wp_ob_end_flush_all() 2 /var/www/vhosts/example.com/httpdocs/wp-includes/class-wp-hook.php(377): WP_Hook->apply_filters() 3 /var/www/vhosts/example.com/httpdocs/wp-includes/plugin.php(523): WP_Hook->do_action() 4 /var/www/vhosts/example.com/httpdocs/wp-includes/load.php(1308): do_action() 5 [internal function]: shutdown_action_hook() 6 {main}
2. We have at least 30 folders with at least 15 years worth of images. Its a lot.
3.
PHP version8.5.10 (Supports 64bit values)PHP SAPIfpm-fcgiPHP max input variables1000PHP time limit300PHP memory limit640MMax input time180Upload max filesize256MPHP post max size256M
Thank you for such detailed breakdown, this is very helpful.
My best guess is that ob_end_flush() error is misleading and it’s just what WordPress logs when a request dies partway through output. The actual problem is that the free version of this plugin scans your whole uploads folder in one request. With that many images, it runs out of memory or hits the 300s time limit before it can finish, which is why raising the limits didn’t help.
Pro version was completely rewritten specifically for this reason. It scans incrementally, so it might be able to handle this properly. Unfortunately, there is no free trial I can point you to, but if you want to try it, there is a 14-day refund period. So you can get a full refund if it doesn’t work on your setup.
