After update to 5.3.4 we get this for each time a new page is loaded :
Call to undefined function acf_is_local_field()
Not a biggie as long as it is not repeating.
I can’t really tell anything by looking at that error report you linked to. Does it say anything about what file and line number the function is called on? PHP usually does.
I didn’t check it but as it says : api-field.php line 117 .
It’s not a biggie , as it is not repeating. You can close this if you can’t replicate it.
Actually, I can’t recreate it, but that does not mean you’re not getting the error. You might have a corrupted file. I would try reinstalling to see what happens.