As the title said, we see too many maps creating this error in gamelog:
"Converting prefab descriptor '...../...../......ppd' version 23 to current version (24)"
The editor will do this conversion for you, you just need to point it to a certain folder.
As an example i am gonna post Roextended Steam shortcut line used to open the map in editor:
"C:\Program Files (x86)\Steam\steam.exe" -applaunch 227300 -homedir D:\Play -edit roexfull -force_mods -64bit -unlimitedlog -conversion_dump_path d:\fullconvert -noworkshop -mm_max_resource_size 100 -mm_max_tmp_buffers_size 1000
RED LINE:
is the path i choose for myself of a folder where the editor will store converted PMD's. You can choose your own.
Open the editor, scroll through Content Browser and "see" all your custom materials,
close the editor and you will find in that folder the new converted PMD's
organized in the same file structure as old ones. Just drag them over your old ones and replace them. Thats it!
(off topic) GREEN LINE: is the path where i keep my Euro Truck Simulator 2 folder dedicated to editing work,
while the normal "my documents" folder is just for playing the game.
full tutorial on Roextended youtube channel