block does not exist error

Excerpts from a reply about a Moodle issue. The issue faced was, an admin block was seen (mistakenly added?) on the RHS of Brickfield registration (admin) page. When trying to delete this block, a 'block does not exist' error was seen.

People have faced this problem, and there seems to be no clear-cut solution - 

https://moodle.org/mod/forum/discuss.php?d=185758

Since this discussion says that the Theme may be responsible,

https://moodle.org/mod/forum/discuss.php?d=353949

I tried changing the theme from Moove to Adaptable, and found that the Admin block appears on all pages with that theme.

I also found that the Admin block is unlocked in this page,

https://our.test.server.org/admin/blocks.php

So, I think it may be safer to not try to delete it via the database back-end, or else it may interfere with accessing the admin console.