“Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent” when calling session_start() first in file [duplicate]

Answer 1

If you have saved your file in UTF-8 format, be sure to check if it is UTF-8 without BOM.

Answer 2

Along with rFactor's response, check that you do not have any white space at the top of the PHP file (e.g. a space or a period).

Answer 3

Changed encoding from UTF8 to ANSI, then saved the file and the error went away.

Answer 4

Did you include this file from any other file? If so, then did those files echo/output anything?

The HTTP header that includes cookies must be outputted before the body (the HTML, usually).