Do not keep retrying a partial update
Create or confirm a restorable backup before changing files, permissions, plugins or themes. If the website still opens, keep a copy of the exact error before making further changes.
What the error means
WordPress could not write or replace a file
Could not copy file, Installation failed and unexpected FTP credential prompts commonly mean the PHP process cannot write to part of the WordPress installation. Causes include incorrect file ownership, unsafe or restrictive permissions, insufficient disk space, a stale lock or maintenance file, and security software blocking the operation.
Safe checks
Check the hosting account before trying again
- Confirm a current backup of both files and database can be restored.
- In Plesk, check the subscription disk usage and remove only files you recognise and no longer require.
- Open WordPress Toolkit and review the site status, available updates and security warnings.
- Record the exact path named in the error and whether it belongs to WordPress core, a plugin or a theme.
- If maintenance mode remains after the failed update, verify the update has stopped before removing only the stale
.maintenancefile. - Retry once after the cause has been corrected, then test the public site and WordPress admin.
Do not set files or folders to 777
World-writable permissions can expose the website to modification by other processes and may not correct ownership. UKC support can check server-side ownership and permissions when supplied with the affected path and time.
After recovery
Confirm the whole site still works
Public pagesTest the home page and important forms.
AdministrationOpen the dashboard and update screen.
Plugins and themeConfirm the intended versions are active.
BackupCreate a fresh known-good recovery point.
Need UKC to check the failed update?
Send the domain, exact error, affected file path, update type, plugin or theme name, time, PHP version, available disk space and whether you have a current backup. Never send a WordPress, Plesk, FTP or database password.
Ask the Hosting team