hmm, trying things here with your copy, it works just as I expect so I must be missing something….

e.g. on your test site, currently being Sunday morning 3rd March when you are closed until 8 , I cannot order anything until Wednesday (6th March – as of course you are closed Mon and Tue)…

So what do I need to do to see what you are describing (and please be specific as to what outcome you would be expecting when doing things) ?

ok, at least its not language related (one less thing to worry about)

>In the subdirectories of my clients, there is no file named “wppizza-customisation.php” at all.

evidentally there is though, otherwise the error:
“Undefined constant “ingrinfo” in /……../wp-content/plugins/wppizza-customisation/wppizza-customisation.php:16”
would not ever be thrown…. ?!?

as a summary here (in case someone experiences the same or similar issue and comes across this thread)

– simply changing the date format in the preorder plugin (ignore WP settings etc) fixes things it appears

As mentioned above, I’ll see if this is fixable.
This may actually involve removing the “26 Feb 2024” format option altogether ….yet to be determined …
In any event, it will be addressed in the next update of the plugin one way or another

@johanfmp
Again , thanks for doing the donkey work here to narrow this down , much appreciated and very helpful

let’s start with the easy pickings first (may or may not be the issue of course)
from your debug:

PHP Fatal error: Uncaught Error: Undefined constant “ingrinfo” in /……../wp-content/plugins/wppizza-customisation/wppizza-customisation.php:16

so you are using a constant that does not exist.
since php 8.2 (or perhaps even 8) this will cause fatal errors – i.e your site just dies – so you need to fix that to start off with (I do not think there ever was a constant called ‘ingrinfo’ anyway unless you defined it yourself ?!)

>Olly, it seems that the preoder (picker) has a problem with the dutch language
interesting and quite possible (may be dependent on date format settings)
i’ll play around with it here to see what is going on (I guess you have your – at least temporary – workaround )

works all fine here with your settings.
your debug however is complaining about session start – for this see here: https://docs.wp-pizza.com/troubleshooting/?section=headers-already-sent
secondly: have you tried enabling the caching bypass option (in the preorder plugin settings ?)
i.e enable
Caching: Turn this off if you experience problems with date/times not being set correctly

without seeing your settings in the preorder plugin , I cannot really comment other than to say , have you enabled debug and checked your debug log to see if there’s any hint there ?
https://docs.wp-pizza.com/troubleshooting/

As of v1.2 you can now enter “-0” (that is: minus zero) into a pickup price and it will hide the relevant menu item from selection (And indeed remove it from the cart if it was added there before when delivery was selected)

hope that helps