php utf-8 Error Message:

Warning: Cannot modify header information – headers already sent

The Arclab MailList Controller HTML Web Form Generator creates a HTML form and the required php code to process it.

If you have edited the php file with a text editor like notepad and saved it, then you might get the error message above.
The reason is the utf-8 BOM (Byte-Order-Mark) added by some text editors, like e.g. notepad.

The php script is in utf-8 format, but does not have a BOM, since the BOM contains chars, which are "sent" before the header function.

 

Sample:

<?php
...
# SHOW RESULT PAGE
header('Location: http://www.yourdomain.tld/success.htm');
?>

 

After you have saved the php file with notepad it will look like this - even if notepad does NOT show the BOM!

<?php
...
# SHOW RESULT PAGE
header('Location: http://www.yourdomain.tld/success.htm');
?>

There are additional chars before <?php.

The easiest way to fix it is to re-create the php file using the program. If you want to edit the php file anyway, then its recommended to use an editor, which does not add a BOM (Byte-Order-Mark) for utf-8 files (or use a HEX editor to remove the BOM afterwards).