I have researched this until I am blue in the face!
So far, no luck.
I have a test site that is running Joomla 3.4 using CB 2.0.7 with JCE Editor, Joomlashine template Decor and JSN Imageshow. I get the following message that appears at the top of the content area of the registration page when I turn on debug.
Warning: Cannot modify header information - headers already sent by (output started at ...plugins/system/jsnframework/jsnframework.php:1) in .../libraries/CBLib/CB/Legacy/CBCookie.php on line 37
Warning: Cannot modify header information - headers already sent by (output started at ...plugins/system/jsnframework/jsnframework.php:1) in ...libraries/CBLib/CB/Legacy/CBCookie.php on line 117
Also, when completing the registration form and clicking Sign On I get the following error in a popup. (The same thing is happening on my live site running Joomla 2.5.28 and CB 1.9.1.)
Session expired or cookies are not enabled in your browser. Please press "Reload Page" in your browser, and enable cookies in your browser. Please refresh/reload page before filling-in.
I have disabled each plugin/extension at a time, changed to a different template, and have had no different results. I am getting desperate! I MUST be able to have new users register!!!
Any ideas? I have tried every fix that I could find here without any improvements.