@BrianNickel I'm seeing the problem for a week now too. From some experiments, I can reproduce the problem on /2.3/questions/ URLs (and others) with message list with 30 IDs totaling 268 chars (the list only). Example of such URL: pastebin.com/biHBsjsC – When I remove one message ID, the problem seems to stop happening. I've seen a similar issue right after 2.3 API release. But it was less frequent and I didn't investigate back then closer. And the problem disappeared after a while. Now it's back and much more frequent (5-10%). Before there was no problem with URLs 900 chars long.