Update Craft CMS, now I get HTTP ERROR 500 I have a site that's been running Craft 3 and has been running smoothly for several months now.

I was going to update a post today, and noticed that there were updates to Craft 3 that needed to happen (there were several craft updates, along with two plugins). I selected the Craft CMS first to update, and after hitting the update button, it did its thing for about a minute, then gave me a message that the update failed. When I tried to go back to my admin panel, I got the HTTP ERROR 500. Same when going straight to the website.

I tried change my php mode from FastCGI to just CGI as suggested in another post, but that hasn't helped. I also tried setting the devMode to true in my general.php config file, but nothing has changed there.

At this point, I'm dead in the water.

Any suggestions?
If the error 500 is displayed by craft, look in craft/storage/logs (i.e. phperrors.log)

Otherwise have a look at the server logfiles, if you have access to them. The Apache (or whatever http server you use) error log might be useful.