Briefly unavailable for scheduled maintenance. Check back in a minute. No .maintenance File

Question

I logged into my wordpress site today, seen fasttrack plugins needs update. So I clicked on the update button. Now I am stuck at this message.

Briefly unavailable for scheduled maintenance. Check back in a minute.

_{(source: wpbeginner.com)}

I have waited around 30 minutes but still same page showing. Now what to do?

I have googled with the error message and found some instruction to delete the .maintenance file from the root folder at server. But when I when to the server there is no file named .maintenance is available there. I also checked for hidden files.

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Update

Found solution, it was litespeed server cache problem. I answered my own question here, so that it will help others.

Answer 1

In my particular case I have found a solution. That's why answering my own question hoping it will help others.

In my case in was litespeed server's default cache problem. I flushed all cache and site working again. So here is my summery.

1. First check, if .maintenance file exist in root directory of wordpress setup, just delete the file. If problem exist after deleting the file or there is no file name like that follow next.
2. As Answered by Earid A in his answer follow these steps, if problem still exist
3. Try clearing all cache, in browser, in your server, check if you are using litespeed server. It has a default behavior to cache every get request. Find litespeed cache module in C-Panel and click the Flush All button.

Hope this will solve the problem.

Answer 2

Go to wp-activate.php

Search for

define ('WP_INSTALLING', false)

Make it

 define ('WP_INSTALLING', true)

If it doesn't help, you need to temporarily deactivate all plugin, any of your plugins may be corrupted. Need to find that plugin. If again you see this, you need to update your WordPress installation.