Hi and welcome to the forum.

You should remove whitespace after the closing ?> tag in conf/_basic_config.php

Full text from FAQ:

If you get this error, it is most likely you recently changed something in a file. The error is caused by added whitespace (space or line feed) *before* the first <?php or *after* the closing ?>. You can remove the error by opening the file stated in the notice and remove the whitespace. Because whitespace is often hard to detect, you may want to use a fresh copy of the file and make the changes anew. Do use a plain text editor like Notepad++ or Crimson Editor for editing B2evo files. Do not use a HTML editor or Word.

sam2kb wrote:

Hi and welcome to the forum.

You should remove whitespace after the closing ?> tag in conf/_basic_config.php

Full text from FAQ:

If you get this error, it is most likely you recently changed something in a file. The error is caused by added whitespace (space or line feed) *before* the first <?php or *after* the closing ?>. You can remove the error by opening the file stated in the notice and remove the whitespace. Because whitespace is often hard to detect, you may want to use a fresh copy of the file and make the changes anew. Do use a plain text editor like Notepad++ or Crimson Editor for editing B2evo files. Do not use a HTML editor or Word.

Ah thank you thank you so much!

No problem ;)

It didn't solve my problem :(
I still have that error message:
http://www.nicoleb.org/b2/

I tried to do the upgrade from 2.4.0 and well, must have screwed up along the way.

Anybody can point me the right way - pretty please?
:)

I just see, it is probably a whole different can of worms and I'll open up a new post