Can anyone confirm that the Mark Packed button cannot be removed even by script?

buttons not in the Button IDs list tend not to have suitescript support

Does it mean that I also cannot throw an error message when that button is clicked?

you can keep your user event script that throws errors

I'm sorry I'm quite confused. I want to avoid any DOM manipulation. Is it still possible through user event script (beforeLoad) (without DOM manipulations)?

the alternate solution listed on that idea is to use a before submit user event script throw an error

Oh okay. Thanks for saving me a lot of time. The alternate solution there won't work for us 'cause we just want to disable/hide the button so the users will be forced to Edit the IF to enter some info relevant for shipping integration and manually change the Status to Packed afterwards.

This really sounds like trying to make netsuite do things that are process problems, not system problems.

Most of the time they do Edit the IF but there are few cases where they accidentally hit the Mark Packed button and that won't allow them to change most of the details anymore due to FedEx/UPS integration. But yeah, I guess we'll just need to remind them again or at least put an 'HTML field' showing 'Do not Click the Mark Packed button.', etc.

I believe hitting that button triggers a specific UserEvent context type, as battk said, you can just return an error on beforeSubmit if that data is missing

There are default data already. We want to force them to check the defaults. 'Cause sometimes the number of packages change, or the item weight, or other default info must change as an exception to the general rules, it's really case-to-case basis. Some of them, for some reason, 'accidentally' hit the button.