There is a scenario that you should aware of it :

1) in a post, if I mark it as solved, the button "set as answer" exists until next refresh.
2) so if I click on this button, Site returns error : "You don't have this permission"

I think this error confuses the Site Admin because it's irrelevant. maybe somethings like this could be better :

Your post is already solved and you can not select an answer as correct one. If you want to do this mark the post as unsolved and then select correct answer!

Thank you.

This section can only be seen by users with a valid subscription.
If you have a valid subscription, please login now

Support is

It is currently off working hours and most of us aren't around.

Rest assured that we will get back to your issues as soon as the day starts tomorrow!

Your time
Stack Ideas time