I don't know what is causing this, but just yesterday I updated to Joomla! 3.3.0, but I don't know if that's a factor in this or not.

I can no longer edit and save K2 items. It allows me to edit an item, but when I click on Save, or Save and Close, I get this error:

An error has occurred.
403 You are not authorized to view this resource
and the button "Return to Control Panel" is below it

This happens with any K2 item, including articles which were originally created with Joomla Article Manager and simply imported into K2 with nothing else done to them. So it's not just with content created in K2, it's with any content in K, whether it was created in K2 or imported to K2.

And, the problem doesn't happen outside of K2. I can still edit these same articles in the regular Joomla Article Manager without any error messages.

I have checked the permissions and I have all permissions in my k2 user group, and in the Joomla user groups, I am in all of them, including Administrator and Super User. I understand that the K2 user groups and permissions apply to front-end editing only. This problem is happening at the back end.

I don't know what to change or what to set to resolve this. I've tried everything, so I'm posting here in hopes that someone has an answer to this. As it is right now I can't edit any K2 items and it has stopped my work.

What are the other possible causes of this error?

Thank you for your help.

Joomla 3.3.0
K2 2.6.8
K2fields 2.0.0
K2 Import 2.0rc1
PHP 5.3.28

Hi. Check again the permissions under K2 parameters, not the K2 user groups. As you correctly wrote K2 user groups permissions are only applied in front-end. Other things you might need to do is try to disable some third-party K2 extensions.

Thank you. I have checked everything - Joomla user groups, ACL permissions in the k2 parameters, k2 User groups and their permissions, access levels of categories... everything. I can't figure out why I am getting a 403 error.

I can create an article in the regular Joomla Article Manager. But I can't create an item in K2. What are the possible reasons I would get a 403 error when creating an item in K2?
Thank you for your help.

The 403 is used to declare insufficient permissions. Try to open Joomla! system debugger to see where the error comes from.