How do I port a project from 4.11 back to 4.9.2

I had the project ported on 4.11 by a team member that left, and now I need to port it back to 4.9.2 ; If I just try to copy paste the content files the 4.9 editor crashes .

Don’t move anything, right click uproject and pick Switch Version option, switch it to 4.9. IF it’s still crashes then i guess it’s uasset incompatibility and there nothing you can do, you will need to reimport everything. If even blurptint assets crashes and you make BP only game then i think you will need to stay in 4.11 or try move to 4.10 preview