Invalid Authentication Token in MECCHA CHAMELEON

You get an authentication / token error at launch or when joining a server.

Try these steps

Fully quit the game and restart Steam so it issues a fresh session token.
Log out of Steam and back in if the error repeats — a stale login is the usual cause.
Check the Steam status page in case the auth/login service is having issues.
Verify the game files in Steam (Properties → Installed Files) after a recent update.
Make sure only one Steam session is logged into your account.

All troubleshooting.

Device-specific notes.

Common questions.