Have you tried:
– deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the default theme to rule out any theme-specific problems.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
I think anyone of the plugin has an auto update.
Let us know When you access the admin dashboard itself it get the message or you manually update the wordpress or any plugin.
If you didn’t do manually means try deactivate plugin one by one and see the update server error message comes up.
If the any one plugin cause this error message means (While deactivate one by one plugin you can check if the message appear or not if it disappear try to find the option in plugin settings to make sure uncheck the auto update option).
Let Me Know if any.
Thanks.
