When troubleshooting error messages similar to “Failed to write file to disk”, the most common causes include:
- The server’s hard drive is full
- The server’s tmp folder is full
- There are not sufficient privileges set to the folder being written to
This error, “Failed to write file to disk”, within WordPress generally means that the tmp folder is full. While there could be other causes of the error, a review of posts in WordPress’ forums shows the issue is most often with your php tmp folder setup, upload_tmp_dir.
If you are an InMotion Hosting Customer
The default WordPress installation with InMotion Hosting has no problems with the tmp folder and how WordPress uploads images. If you are getting this error, Create a phpinfo.php file and check what the “upload_tmp_dir” is set to. If it is set to:
- “no value” – WordPress is defaulting to the /tmp folder on the server. This is rare, but the /tmp folder may have become full. Please contact our Support Department for further assistance.
- something other than “no value” – It would appear that you have a custom folder set for your upload_tmp_dir. Please ensure that you have that folder’s permissions set to 755.
If you are not an InMotion Hosting Customer
If you are not an InMotion Hosting customer, the same items as above generally apply. If you have not set a custom upload_tmp_dir, then you’re using the server’s default tmp folder and you should contact your host and ask for help with checking to see if the /tmp folder is full or not.