Unable to grant admin rights due to error

No, clicking the “Grant Admin” button works.

The full process is like this:

  1. I click the “Grant Admin” button, application presents me with a modal “We’ve sent you an email to verify the new administrator. Please open it and follow the instructions.”
  2. I click the confirmation link in the email (“Confirm Administrator Account”) which brings me to a confirmation page.
  3. On the confirmation page I click the button “Grant Admin Access”, which then produces the error page (see screenshot in my original post) and also the error messages in the log.

I also just noticed the following message further up in the log (prefixed with the number 46 - does this mean that it has been repeated 46 times?):

Error ensuring consistency for Group: Validation failed: Name has already been taken