[SenHeng]

Echoing your experience, I too worked on a project that was stuck on angular.js 1.3 when 1.6 was about to be released. We took a look at some migration guides and didn't see that many changes we had to make, so we tried updating it.

Everything broke.

Investigating, I realised that one of my long departed predecessors forked angular-bootstrap and made a few small changes to it. The problem was that the that library was tied to angular.js 1.3. To update angular.js, we had to update the library. To update the library, we had to remove all the changes in which would break large parts of our UI. The project was already in maintenance mode by that time and we decided to just leave it as is. I spent the next month converting it from coffeescript to es6.

[rpep]

I had exactly the same thing last year with a previous long departed staff member having forked django-flex-fields into their personal GitHub and having made substantial changes. Porting to Django 3.2 then became a huge and costly project in itself as a result.