Upgrade :Error 500

You’re hard to help, because you try everything before asking. Does the error come after clicking the login button in wp-login.php? If so, what’s the first URL in your URL bar immediately after clicking the login button? If the error occurs when visiting wp-login.php, I’m having no trouble getting to yours.

https://www.domain.com/wp-login.php displays fine
Enter details
Click Login
URL stays the same, 500 pops up
And it’s not my blog ??

Oh, it’s not your blog, lol. Well, if you’re out of ideas, then so am I. I’ll try to sleep on it and maybe I’ll dream something up.

Erased all files and reuploaded – no go.
Checked various db settings against my blog – all seems good
Tried another ftp client for deleteing / uploading / viewing files – no go.
Error log still being obtuse.
Running upgrade.php goes well, but still no-go.
This is either blindingly simple or it will never before have happened in the known universe …..

From https://www.checkupdown.com:
Introduction
Your Web server encountered an unexpected condition that prevented it from fulfilling the request by the client (e.g. your Web browser or our CheckUpDown robot) for access to the requested URL.
This is a ‘catch-all’ error generated by your Web server. Basically something has gone wrong, but the server can not be more specific about the error condition in its response to the client. In addition to the 500 error notified back to the client, the Web server should generate some kind of internal error log which gives more details of what went wrong. It is up to the operators of your Web server site to locate and analyse these logs.
500 errors in the HTTP cycle
Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with your Web server:
* Obtain an IP address from the IP name of your site (your site URL without the leading ‘https://’). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
* Open an IP socket connection to that IP address.
* Write an HTTP data stream through that socket.
* Receive an HTTP data stream back from your Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.
This error occurs in the final step above when the client receives an HTTP status code that it recognises as ‘500’.
Resolving 500 errors – general
This error can only be resolved by fixes to the Web server software. It is not a client-side problem. It is up to the operators of your Web server site to locate and analyse the logs which should give further information about the error.

Thought so …. and given the lack of detail from the CPanel (I really don’t like them you know) I’m declaring this a ‘hitherto unknown enigma’
??
(and plans are afoot to nuke it !)

I’m getting this same problem at https://www.mostlymuppet.com/

Followed upgrade instructions step by step and now I’m looking at an error message and not my blog.

Never mind. The root of my problem was the failure to delete .htaccess before upgrading.