Solved

Bug éditeur de livrée

Impossible d utiliser l éditeur de livrée même quand je télécharge le fichier ça ne marche pas

pareil ici.

Are you using the Firefox or Edge browsers?

Pinned in the very top of the help & support section. https://igpmanager.com/forum-thread_1/6269
Reply #14 has link to a Firefox installer to get plug-ins to run again on Firefox, it's available up to early 2018 and works on Firefox versions 52+.

and for chrome ?

ne fonctionne pas

Hello Alban, there is no official support for Chrome, but somebody shared an extension that might allow you to do it in Chrome in the thread I've linked in response to Mik Mak.

Hi Mik Mak, if you're having issues please post in this thread for support with the Livery Editor.

I recommend Internet Explorer to access the Livery Editor as it is the simplest way to access it after downloading the Unity Web Player.

Leo, if you're still having issues, may I suggest asking for help on the thread I've linked above.

All future issues regarding the Livery Editor should be posted in the thread I've linked in this post.