Panel saving errors

Hi all, I logged in my panel today and it won’t let me save changes anymore. I get the following error messages when I for example want to more a sequence of images or when I want to edit text or when I want to publish a section.

Exception: undefined
Unexpected token < in JSON at position 0

I tried to install the site in a new folder on the same server, same happens there.

Can anyone help?

Thank you

Have you made any changes between you last logged in to the Panel and now?

Yes I made changes to css and added a fancybox.

But nothing that affects the Panel, like adding hooks or Panel plugins?

Is there any more information in your browser console, maybe?

What is your current Kirby version?

I can’t find anything regarding this particular error and if file permissions were wrong, the error message should actually look different. But have you made sure all folder and file permissions are correct and owned by the Apache user?

The error is also different from things reported here but it might still be worthwhile to go through the troubleshooting list:

Thank you I need to check permissions and will read troubleshooting list.

If that doesn’t help, try deleting session data, the browser cache and the session cookie. Then try again.

Also, you might want to update to the most recent Kirby release (3.1.3) if you haven’t done this yet.