If the program is running
Few notes based on the following user posts:
There are several solutions:
1. Blank lines :
Make sure no blank line after of the calling php script.
Check is not followed by a blank line, in particular, include or require the file. Many problems caused by these blank lines.
2. Use exit statement (with the exit to solve):
Use exit after header statement seems to help some people
After the header with exit ();
header ("Location: xxx");
3b. Use output buffering (use output buffering to solve):
... HTML codes ...
... PHP codes ...
header ("Location: ....");
4.set output_buffering = On in php.ini
set output_buffering = On will enable output buffering for all files. But this method may slow down your php output. The performance of this method depends on which Web server you're working with, and what kind of scripts you're using.
5. Remove bom.If you use utf-8 encoding, must be removed in the UTF-8 BOM, this is because utf-8 encoded file containing the bom, php4, 5 are not supported by the bom.
This address is http://www.computerites.com/web-design-skills/2011/12/cannot-modify-header-information-24.html