Illegal choice when 'watch' is shared in watcher module

I cannot replicate this problem. It's likely caused by another module.

Try executing this SQL query: "TRUNCATE cache_form;" and see if it helps.

I had the same problem, I think. My mysql doesn't like having single-quotes in a permission. So I removed the single-quote from "others'" everywhere it appears in watcher.module and am living with being grammatically incorrect. (I also changed the enclosing quotes to single quotes, but that probably didn't matter). But the error went away. I'm actually using version 5.16, but I suspect its the same issue.

Not sure I'm following, did or did not removing the apostrophe fix the issue?

I don't get an error when saving the permissions anymore.

Understood. Apparently one or more modules cause this issue as it doesn't happen on a fresh install of Drupal. I'll remove the apostrophe as it's an easy fix.