How can I fix this ?

Message Severity: 3
C:\Battlefront2\main\Battlefront2\Source\EntitySoldier.cpp(10505)
EntitySoldier "cis_hero_grievous" missing animation bank "grevious"

Message Severity: 3
C:\Battlefront2\main\Battlefront2\Source\EntitySoldier.cpp(10536)
EntitySoldier "cis_hero_grievous" missing lowres animation bank "greviouslz"

Well, like the error says, you are missing the grevious animation banks. So copy the grevious files from the assets to your custom side's munged folder.

thanks,but after the manual clean it suddenly appears on every map with maul etc.
and deathstar is crashing and hasnt a message 3 but why ? :/

What appears on every map with maul? The same type of error message? If you are adding hero units to a custom side, you will need to copy over each unit's animation banks files to your custom side's munged folder, not just for Grevious but for every unit. Look in the unit's odf for "animationbank" or "skeleton" if you aren't sure which files these are.

And what do you mean the Death Star is crashing? Did you overwrite the stock units with custom units? Or did you add a new mode to the Death Star? Or something else...? Please post your LUA mission script if so.

I made a new manual clean and it works now.
But thank you