This happened when registering

[SapphirePhoenix]

Inside functions/functions_forums.php, which relies upon the information above being correct, the line the error is happening in is the function mybbsetcookie() which is called in mybbregister(), also in that file, from the file register.php. This should be working just fine - so long as nothing is being rendered to the page BEFORE this happens. Can you verify for me that absolutely no changes have been made to register.php by putting in a copy from a fresh version of the files?

But this isn't the only place where problems could have occurred. Afterall, $mysidia->user->register(); is called before mybbregister() and if it attempted to render anything to the page, even a blank space, this error would be happening. I'm pretty sure that function is being called up from it's location in classes/class_visitor.php (since the visitor class is what actually registers users and extends user) and it's register() function. All this function should be doing is adding a user to the database. Definitely not writing anything to the page, so it shouldn't be interfering. Put in a fresh copy of classes/class_visitor.php to confirm no changes were made here from the default?

I believe the problem is probably that part, but I have checked that the files weren't edited. But then this:

Afterall, $mysidia->user->register(); is called before mybbregister() and if it attempted to render anything to the page, even a blank space, this error would be happening.

Is something that I'm not 100% sure about, so can you please explain?

EDIT:
Also, I have noticed that when I registered on other Mysidia sites with integrated forums, the same error shows up.