I have a site in development, that is basically crippled, because of this issue.
I was installing an additional module when I got:
"The website encountered an unexpected error. Please try again later."
I have encountered this error quite a bit in Drupal 8.x, typically, I was able to simply click the "Back" button on my browser, and save again, and I was fine; but in this instance, I am basically stuck; as the site is now completely locked up. I can click "back" and get to the previous screen, however ANYTHING I attempt to do, yields the "The website encountered an unexpected error. Please try again later." message. I cannot even view the front end (even from another machine).
The site is "Online", while not yet a "production site", it is on a live host. I have gone in and deleted the folder for the last module I installed, and I have cleared the cache, both with Drush and via PHPAdmin, but no change.
I'm not even able to get to the area in the admin menu to view error logs.
I would appreciate any help resolving this.