Re: Warning: Invalid argument
The bug you have run into is fixed in the latest trunk release, or you can see this thread and this post specifically about the change to make:
It’s been discussed before as well:
https://bbpress.org/forums/topic/installation-problem-cannot-modify-header-information
It’s just a php warning, and your server is configured to show warnings, so you see it. It does point to a problem with the code, but even with the warning, everything still works fine.
