WordPress Update Failed

Hey there,

In this case, when WordPress puts itself into maintenance mode, it does so by creating a file named “.maintenance” in the installation directory

You can log in via your hosting provider’s file manager or FTP and delete the file:

View post on imgur.com

Also, make sure to clear the cache after it. This guide can help you:
https://www.hostinger.com/tutorials/wordpress/how-to-clear-wordpress-cache

And then try updating WordPress again