This error message comes from Joomla's hidden field and only happens on PHP 8 where strict type matching is enforced. It complains that one of the configuration values contains a PHP array instead of a string.
The thing is, we are only using 5 hidden fields, four of which store a value of 0 or 1. The only one that's supposed to store a comma-separated list (NOT an array) is the list of Super User groups. There was a bug which would save an array instead of a comma separated list but it was fixed on June 5th, 2020.
Is this an old installation of Admin Tools? If so, I have an idea on how to fix this. I just need this bit of information to make sure I don't start heading the wrong direction.
Nicholas K. Dionysopoulos
Lead Developer and Director
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