[_ck_]

“Cannot modify header information – headers already sent”

is one of those errors that will fool you by distraction because it’s an indication of another error, that happened before it, it’s not the actual primary error.

“headers already sent” means one of the following (among other possibilities)

1. You have whitespace at the start of end of a plugin (or template) BEFORE or AFTER the <?php ?> (usually after the end. Whitespace means new lines or spaces.

OR

2. Another plugin or configuration error has occured and sends a text message, which causes the headers to be sent. To find out what the real problem is, you typically can do a “VIEW SOURCE” on the page (from your browser menus) and you’ll see in plain text at the top of the page the real error before the “headers sent” error.