If an automated WordPress update has failed to complete and you are called to attempt the update again
You may have tried to update some themes or plugins in WordPress without success. Your site became unavailable perhaps, then it started to function again and you managed to install your updates.
Although your second attempt was successful, WordPress keeps giving a message at the top of each admin page, that “an automated WordPress update has failed to complete – please attempt the update again now.”
To get rid of this irrelevant now message, you have to use an FTP client or the File Manager of your hosting account in order to delete a file named .maintenance from the root of your WordPress installation.