There are several pretty good guides. 6 to 7 is a bit tricky. 7 to 7.5 is a bit of work too and anything after that is very smooth.
6 to 7 check out
If you are using composer for 6 then you need to convert this to new blocks functionality.
7 to 7.5 check out
Main issue here is to convert files to new media files that 7.5 uses. There is a tool to convert all old files to new media content.
After 7.5 it's a piece of cake to upgrade with nuget packages from visual Studio. Might as well go to latest version 9 (at the time of writing)
Looks promising for the content migration to blocks yes. Didn't know about that tool :)
Remember to backup both database and files after each step. You will likely run the upgrade quite a few times :)
Having a fresh alloy demo site of each version with correct config everywhere is also good.
Yes Daniel will take care of that. Thanx for help...!!
Could you please guide us the best possible way to migrate a Epi 6 site to Episerver 8 or 9.
How does Composers in Epi 6 migrate and to what.