Someone asked me to check on his Wordpress site. Can't upload media. 'Failure to write to disk' Updating fails too. Directory and file permissions are ok. Server has enough space. Cleared tmp. Any more ideas?

Any server filesize upload limits, or filetype limitations. How big is the file he wants to upload? Ask him to wetransfer.com the file to you, so you can see what hapoens and see what error logs are saying. I dont do wordpress but this is where i would look first.

Check PHP.ini

Nothing really to do with limits. I have checked it's at 20mb and the image is 46kb.

Is it a VPS? Can you try to login as the user the site runs on and write a File?

WordPress user permissions?

Is the file that perform the writes owned by a specific user (often www-data with Apache) which has write permissions in that folder? I had this issue yesterday myself.

Apparently it was htaccess. Someone had modified it.

Will keep the recommendations in mind though. Thanks guys