From which version are migrating? It's in general better to start at the bottom of the Migrating your code (https://www.llblgen.com/Documentation/5.11/LLBLGen%20Pro%20RTF/migratingcode.htm) documentation for the version you're starting from. A lot of the breaking changes might not affect you tho, but some are big, like the move of the csproj file locations in 5.4.
It's not needed to migrate first to a given version e.g. 4.0, make that 100% runnable and then move to v4.1 etc. as that's a lot of work. If you're using adapter, the one thing you have to do is make sure you read the top of the migration document so you know you have to move the csproj files, then generate for v5.11, the latest version on top of your code and start migrating your code using the migration document.
The idea is that you have a license of the version you start from and you migrate to a version you also have a license for. Older versions can be obtained under My Account (after logging in). Each major version requires a specific license. If you have v2.8 now and want to migrate to v5.11, and you want to use every version in between we need to send you a license for each version (which is free of charge for a valid v5 subscription).
