John, I’ve done as suggested however now I can’t reproduce the issue!
I downgraded PHP from 7 back to 5.6 and attemped the page update again and the blank value is now saving as it should. The post array was as expected, the field was present and empty and that was saved to the database.
I would say the issue is related to PHP somehow, either a setting in php.ini, mod_security rule or perhaps Suhosin (but I don’t think Suhosin was the issue).
Thanks for your help.
All the research I’ve done leads me to believe that it has something to do with this Sohosin extension. I don’t know anything about it, but it seems to me to be another attempt at protecting php coders from themselves.
One thing that I did find out is that Suhosin sets max_input_vars to 200, this is an extremely small number. At a minimum, using ACF, this should be 2000. Not having this high enough can cause all kinds of strange behavior.
My only doubt in regards to Suhosin is that I have it running on all other versions of PHP that are installed (5.3,5.4,7.0) and the issue isn’t present. The issue was only in 5.6 and now appears to be gone in 5.6 as well after upgrading to 7 and then back down to 5.6. I haven’t modified Suhosin settings in any way.
The max input vars setting hasn’t changed for me, it’s always been set at 1000.
Suhosin is excellent in a shared environment for stopping all sorts of nasty php vulnerabilities.
If the issue rears its ugly head again I’ll be sure to come back here and update the post.
It would be appreciated, as well as anyone else that has information. I’ve never had the problem, but that doesn’t mean I never will and I’d really like to know how to fix it when it eventually happens to me 😛
Please add the following directives to php.ini – it should work!
suhosin.get.disallow_nul = 0
suhosin.post.disallow_nul = 0
