Hi Elliot, Anja,
Update.
I wanted to test if maybe a specific ACF field type was causing the error. So I put a field group back in draft status. It had only 1 text field. And right away the problem was solved. So I did put the field group in published status to check if the error was back again. But the error did not happen! until now I was still in the Twenty Thirteen theme with ACF as only plugin. I turned on all my plugins, still working! turned on my custom theme, still working!
(to be complete, I also had to put some widgets back because the were lost after theme en plugin changes)
So for me, putting a field group in draft status and publish it over again helped to solve the problem.
I hope this helps you.
Best regards,
Dennis
Hi Elliot,
I also migrated to WP3.6 a week ago. Today I had to adjust a slug of a post and I had the the same error. Also I deactivated all plugins and changed theme to Twenty Thirteen. Only when I active ACF and I go to post-types where I have ACF fields the error happens (my test is the slug-edit button and the screen-option tab).
I still testing further, but because I mention to Zartgesotten that only she has the problem I thought I inform you that she is not the only one.
Best regards,
Dennis
