Failed to create forum account

[Kyttias]

And you've not done anything else to modify the process of registration or logging in? Where are you hosted? You can confirm that you can log in to the admin side of your forum just fine (yoursite.com/forum/admin)? I also need to make sure your inc/config_forums.php is set up properly, but I'm just going to assume it is and you can access the forums just fine you just happen to get a header warning upon account creation.

One out of three people I helped with this also had this error but we never did pinpoint the problem.

See, I don't have this error. I have MyBB v.1.8.3, started with no users beside myself (so the very next user I add has a uid of 2, it does not jump to a higher number suddenly in the database, because I never ever deleted anyone), but also:

I have this mod installed which jumps directly from login to the index, which could prevent the headers from being resent.

Even when I change my error_reporting settings to make sure warnings will be shown I absolutely do not get this error when making a new account.

I'd like you to do three things:

• Answer the questions in my first paragraph.
  
• Confirmation you are on a fresh install or properly deleted all test users besides the admin before starting forum integration. The uids in `adopts_users` definitely have to go 1, 2, 3, etc. You should make sure your `mybb_users` tables has uids in the exact same order matching the usernames exactly. While this *should not* be related to the problem, it is a separate, serious problem.
  
• Install the mod mentioned above.

Step three may entirely fix everything, or, something else could be wrong, so no guarantees. But I'll need all this information to help.