I recently updated a WordPress site to 5.3 but the update didn’t finish. The instructions were to read the email in admin email. I didn’t get the email. After a Google search I ended up on this page which helped me solve the issue.

https://www.wpbeginner.com/wp-tutorials/how-to-fix-another-update-in-process-error-in-wordpress/

The site was local so i just deleted the entry in the database under the “wp_options” >> ” core_updater.lock “. I was able to run the update without a hitch.

I hope this helps someone else out there…