How to find non upgrade-safe modifications?

Hello,

I’d like to upgrade a 7.9.1 to 7.10 and later.
For some modules, there are some changes in PHP and templates / JS and I’m wondering how to find them.

I’ve downloaded the live version and ran a diff over all folders with the 7.9.1 from the official downloads.
There are 427 files in the modules folder alone (many are languages - 2 additional languages are installed on the live version).
How can I find the files that have actual custom code inside?
(No documentation or similar - but at least in the invoices are product images in the line items, so there are differences)

You’ll have to use file patterns to narrow down those diffs, there is no other way, if you didn’t keep a list…

I’d say the general idea about non-upgrade safe customizations is this…

  1. Don’t do them. It’s rare that they are really necessary.
  2. If you do them, keep it tidy, make sure you keep a list, or at least add a recognizable string (MyCustomCodeStartsHere, MyCustomCodeEndsHere) everywhere you make them.

Another thing you could try is run a git pull of the new stuff on top of the old stuff, and work through the conflicts manually. This should take you directly to all the problematic stuff. But it will get messy and confusing, so I don’t recommend doing it live on the server, you should rather try it in a testing environment just to learn about your custom code locations.