Weedpacket My principal recommendation is to go through the relevant Upgrading pages of the manual; all the ones between the "from" version and the "to" version. Skim-read first, then pay a bit more attention to incompatibilities and see if anything there rings a bell.
I have certainly been reading those, in particular these backward-incompatible changes. The 0 == ""
seems like it might be a problem. It's always helpful to hear from folks who have practical experience.
NogDog Hmm...not really, other than it probably would have been easier for me if the old PHP app I was working on was more modular and leveraged compose and such for external modules. The one good thing was that we had a fairly extensive test suite for the main part of the app (it's API endpoints), so a lot of it was run the tests, research the resulting errors, fix them, search for other places in the code we used the offending function, syntax, whatever, then rinse and repeat.
Assuming that the composer packages you use would be updated by their maintainers. I see the wisdom of the test suite. Did any 7/8 problems seem to be especially common? I'm imagining I'll be examining a lot of equality comparisons in if and switch statements.
NogDog The good news is that as part of it, I simplified how the Docker images were built...
Interesting to know you are using Docker. I was using virtualbox for virtual machines some time back and it seemed so cumbersome. I need to hone my virtual machine chops.