Cannot modify header information-headers already sent by ...

This problem was actually listed in the "Common problems" section of the installation instructions, but many users only M to run in it when they start configuring their site after the initial setup. So this we go again:

This is commonly known as the "whitespace problem".

The error message typically looks something like

Warning:cannot Modify header Information-headers already sent by (output started At/path/to/geeklog/public_html/config . php:581) in/path/to/geeklog/public_html/system/lib-sessions.php on line 180

(Line numbers and file names may vary). The problem is this many editors seem to add additional blanks (spaces) and/or empty lines in the end of a file when you E DIT it. This so-called whitespace are then sent to the browser when the file is loaded and interferes with the header of a page tha T Geeklog tries to send to the browser often causing problems as login such.

The fix is, obviously, to remove this whitespace from the file. Read the error message carefully. It says "output started at ..." followed by a-file name and a line number. That's the file (and line), need to edit. Ignore The second file name-that is only a file that included the has the file. The the ' one ' is the ' one ' have to edit and not the second one.

Since the editor you ' ve been using caused this problem in the ' I ', you should use another editor to fix the proble M and remove the whitespace. The forum thread for some recommendations for editors to use on Windows. Unix/linux users can ' t go wrong with VI.