It happens a lot when trying to upload attachments or images to the media gallery. I increased the following options in php: upload_max_filesize=800M post_max_size=800M max_execution_time=300 max_input_time=300 However I still get "There was a problem uploading your file." as an error. I'm using CentOS 6.6, php-fpm and nginx. Could this be somehow related to nginx? edit: Ugh, I feel so retarded now. I forgot about nginx at all. I added client_max_body_size to the http block in nginx.conf, restarted both php-fpm and nginx and now it works fine.