How to fix mismatch file errors when playing online when trying to join a server.
How to Fix
A Rainbow Six 3 PSA for everyone who had recent R6 3 map packs experiencing Coastline_T or R6RUSS mismatch errors when joining the Rainbow Six 3 servers
Find those files in your game’s textures (.utx) folder and delete them. Thats it.
These files are outdated and will be coming in a new 2020 map pack later this summer after I release a couple more new maps. (This is why I hate downloading mods manually.)
AND AS ALWAYS SET CONNECTION SPEED TO T3 IN OPTIONS MENU so you can download things in game faster and not lag.
This same thing is what you do for any mismatch file actually. Usually they are often either in the textures folder or staticmeshes (.usx) folder but occasionally others. Especially if you tried to download single player mods then tried to play online with the same copy you modded. To get around that, make a clean second install of the game just for multiplayer.