Fixed: WordPress failed to write file to disk

How to fix “failed to write file to disk” in WordPress

Start with file permissions and work through the list. Most users can fix the issue without touching advanced server settings.

1. Check and reset file and folder permissions

WordPress files and folders need the correct permissions so your web server can write to them.

What permissions should be:

• Folders: 755
• Files: 644

How to check and fix this using cPanel File Manager:

• Log in to your hosting control panel (e.g. cPanel).
  
• Open File Manager and go to your WordPress root directory (usually public_html).
  
• Navigate to wp-content/uploads/.
  
• Right-click the uploads folder and select Change Permissions.
  
• Set the folder to 755 and apply changes to subfolders.
  
• Check individual files (like uploaded images) and set them to 644 if needed.

Using FTP (e.g. FileZilla):

1. Connect to your site with FileZilla.
   
2. Locate /wp-content/uploads/.
   
3. Right-click the folder, choose File permissions, and set to 755.
   
4. Check the box that says Recurse into subdirectories and apply to directories only.
   
5. Repeat for files, setting permissions to 644.

Avoid 777 permissions. It might fix the error temporarily, but it opens your site to serious security risks.

2. Update file and folder ownership (advanced users)

If your files are owned by a different user than the one PHP runs under, WordPress might not be allowed to write to them, even with the right permissions.

This usually happens when:

• You move your site between servers.
• You switch between FTP and root SSH users.
• You’ve restored files using root privileges.

How to check and fix via SSH:

1. Connect to your server using SSH.
   
2. Run ls -l in your WordPress directory to check ownership. Look for something like www-data or apache as the owner.
   
3. To fix ownership, run:
   
   sudo chown -R www-data:www-data /var/www/html
   
4. Replace /var/www/html with your WordPress path and www-data with the correct web server user.

This step requires root access—if you’re on shared hosting, you’ll need to contact your host.

3. Clear or recreate the PHP temporary folder

Before WordPress stores an uploaded file in wp-content/uploads/, PHP places it in a temporary folder. If this folder is missing, full, or not writable, uploads will fail.

How to find your temp directory:

• Create a new file called phpinfo.php with the following contents:
  
  <?php phpinfo(); ?>
  
• Upload it to your WordPress root and visit yoursite.com/phpinfo.php.
  
• Search for upload_tmp_dir. If it’s blank or the path doesn’t exist, PHP can’t store temp files.

To fix:

• Create a new folder for temp uploads, e.g. /home/user/tmp.
  
• Make sure it’s writable: chmod 755 tmp
  
• Edit your php.ini file (if you have access) and add:
  
  upload_tmp_dir = “/home/user/tmp”
  
• Restart your web server (Apache or NGINX) for changes to take effect.

If you don’t have access to php.ini, ask your hosting provider to set the upload_tmp_dir for you.

4. Check disk space and hosting quotas

Even with perfect permissions, uploads will fail if your server is out of space or file quota.

On shared hosting:

1. Log in to your cPanel.
   
2. Check Disk Usage under Files.
   
3. Look for storage limits or inode (file count) limits.

On VPS or dedicated servers:

1. Connect via SSH and run:
   df -h
   
2. This shows disk space usage across mounted volumes.

To check inode usage:

df -i

Fixes:

• Delete old backups or media files.
• Clear server logs or email queues.
• Upgrade your plan if you’re constantly hitting limits.

5. Disable plugins or security software temporarily

Sometimes, a plugin might block uploads by modifying permissions or interfering with file operations.

How to test:

1. Go to Plugins > Installed Plugins in your dashboard.
   
2. Deactivate all plugins.
   
3. Try uploading a file again.
   
4. If the upload works, reactivate plugins one at a time to find the culprit.

Also check:

• Security plugins like Wordfence, Sucuri, or iThemes Security
  
• File managers or upload restrictors

Once you find the problematic plugin, contact the developer or find an alternative.

6. Contact your hosting provider

If you’re not comfortable changing permissions, editing config files, or checking server storage, your hosting provider can help.

Include these details when submitting a ticket:

• The exact error message you’re seeing
  
• What action triggered it (uploading an image, installing a plugin, etc.)
  
• Any recent changes to your site or server

Many hosts can fix the issue in just a few minutes.