Q:

Some chat users have gravatars with no hash in the URL

http://chat.stackoverflow.com/users/2925837/hasan-alaca
http://chat.stackoverflow.com/users/2758236/lugia101101

Both have this gravatar URL: https://www.gravatar.com/avatar/?s=128&d=identicon&r=PG&f=1
I've already seen this behaviour a few days ago. Both users have proper gravatar identicons on Stack Overflow and one of them has an email set so it's not caused by the fact that the other one does not have an email set. I tried refreshing the chat profile of the user with the email to be sure chat knows about the email, too.

A:

Yes; there was an API change in the internal communications between chat and stackoverflow - it was still returning a url, so the change wasn't flagged - it just wasn't always a useful one. This has been fixed and will be deployed next build.

