Explanation of why you could not delete your old Google Reader tags/folders
Mihai P. has posted an answer to the question "some of my tags cannot be removed":
There were two problems:
We used to maintain a list of deleted tags. However, the place where that list was stored had an upper bound on how large data could get, so it was possible for the list to get to be too large, and you could no longer delete any tags. We changed it so that deleting tags would actually delete them (instead of adding them to the "deleted list"), which removed that limitation.
Once we did that, we ran into a secondary issue where old tags (created more than a couple of years ago) were not storing their "owner" in the same way, so the ownership check in the delete operation (to make sure the requesting user has permission to delete that item) was failing. We changed the delete operation to correctly determine the owner for these old tags too.
A member of the Google Reader team kindly explained why many of us were having problems deleting old tags/folders from Google Reader. Apparently it is due to the way a) Google Reader dealt with deleting tags and b) ownership issues.
Very interesting and I think it’s great that they’ve finally come out and shed some light on a situation that has been going on for several months now. I really appreciate the fact that they went out of their way to explain why the problem was occurring and what they did to fix it.
I can say that I was able to finally delete that tag that I could not delete.