Just want to add my voice to this issue as it’s been happening to the sites I run ACF on since 6.3.6. I tried @clicknathan’s fix using Geoffrey’s method but it didn’t work for me. Was running 3.6.11 and still got the error. Only thing that’s worked is rolling back to 3.6.5. Since reverting a week ago I haven’t seen the error.
It would be great if this issue could be resolved soon.
