Hey there, we had some fixes to make our side which we did in 6.4.0.
This issue hasn’t come about because of an ACF update, however – it’s WordPress 6.8 which has triggered the error. Our fixes brought our core to be compatible with WordPress 6.8, but the error can still happen if your code triggers ACF to initialise early. We could prevent ACF ever initialising early, but that would result in broken sites, rather than sites with warnings, so it’s definitely not the best option here.
We’re looking at adding a _doing_it_wrong additional notice in our next release if you trigger this error, which would help you figure out where the problem is in your code at the expense of double the notices.
For now, your best bet is to check your functions.php file for get_field or acf_add_options_page as they tend to be the two places we’ve seen most commonly trigging this.
Thanks,
Liam
