It recently happened to me a couple of times that I want to add a tag wiki suggestion, but only get the general Opps error page after submitting the edit form. The tag wikis is question were previously empty. It happened just now with the url
tag.
Between these occasions I was at least once able to submit one successfully, so it doesn't seems to be a permanent error.
Did anyone made the same experience? I wonder if this is a real error or just some funny "access denied" message. Maybe there is already a suggestion for this tag wiki in the queue or something.
This morning (22th Feb) it worked again. I will wait until it reappears before reporting it to the SO/SX people.