My site has been updated automatically to Wordpress 4.9.3. After that, there is one error message in error log :

PHP Fatal error: Call to undefined function request_filesystem_credentials() in ../wp-admin/includes/class-wp-upgrader-skin.php on line 93

How can I resolve this message?

Thank you.

  • 2
    Can you update to 4.9.4? Alternatively try downloading the WordPress files from the official source and uploading them again via FTP
    – kero
    Feb 7, 2018 at 13:26
  • The official WP news has information about this, upgrade manually to 4.9.4
    – Tom J Nowell
    Feb 7, 2018 at 13:44

1 Answer 1


Upgrade manually to 4.9.4, it's a known issue with 4.9.3

  • 1
    See Release Post on Make and the Technical Overview of what happened for more information.
    – Howdy_McGee
    Feb 7, 2018 at 16:18
  • I have an extremely tweaked wordpress instance running live, and as legends said, doing this is the biggest mistake, but now I am being new to team. I do not have option to suggest a new scratch project... now in this case, how can I resolve this error without upgrading the wordpress version to the suggested one Mar 22, 2018 at 5:09
  • 1
    Upgrading manually will do the same things as the auto-updater, if you've modified WP Core itself then you'll need to do the process by hand, there's no way around it, it's unavoidable. You can replace core mods with proper built functionality piece by piece, using filters etc. Keep in mind too that by modifying core the security of core is compromised, you could face serious issues going forward, especially if there's a data breach
    – Tom J Nowell
    Mar 22, 2018 at 13:57

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