It might save you some time and headaches to go to 2019 from 4.50.08 and then do the 2021 upgrade.

If you can find a 2017 version,  that is the best middle of the road migration path. If not, 2019 is your next best choice.

Here are my notes as I'm working on a slightly older migration ( 3.6 ) to 2021.

Updates and corrections welcome.

Note that in my case I did not have PAYROLL or any 3rd party integrations which needed to be considered: 

docs.google.com/.../edit

Thanks Wayne for posting the details. My post was just a heads-up that this is a multi-version migration and going direct to 2021 doesn't work. (at least for me)

The only issue I had to work around is Sage 100 insisting on setup of its 'CC vault' before moving forward.

Thank you all for this great info. I decided to go to v2017 first and then v2021. I will post anything unusual I run into to help others who might have this type of upgrade as well. Much appreciated!