I have a complex website built with 3.0.5 and i need to upgrade it to 4.0.0-alpha6.

What I've done so far

* I changed composer.json with the version I want and run 'composer update'
* I replaced all the old modules with the new versions that support 4.0
* Now I keep getting errors/incompatibilities. When i fix something and refresh I get another and so on.

My questions:
* Have I approched this update the right way? If not what should I do instead?
* I've seen some available tool to namespace classes but chouldn't really understand how that works, so no success there either.

I would appreciate any kind of help here.
Thanks,

OK, this is a lot later then it should be, but in any case:

First I would wait for the first beta version before upgrading a complex site - because untill then the API is still subject to changes. Second there are a lót of API changes, so you'll have to test and update every bit of your custom code!

As to namespacing, I use netbeans and if I type 'Use SomeClass' it will automatically show me the proper namespace...

There's this:
https://docs.silverstripe.org/en/4/upgrading/
https://docs.silverstripe.org/en/4/changelogs/4.0.0/#a-name-upgrading-a-upgrading (not sure how up-to-date)

And possibly this:
https://github.com/silverstripe/silverstripe-upgrader

Working with images has changed enormously - there is a task in /dev/tasks/ that may help importing existing images (haven't tried)