Rainbow Six Siege: Using Steam Free Weekend Game Files on Uplay

Perhaps, like me, you decided to try out Rainbow Six Siege on Steam during a free weekend.

Perhaps you found that you liked the game.

Perhaps at the end of the Free Weekend you purchased the game outside of Steam, using your new key to activate the game on Uplay.

Perhaps Uplay asked you to re-download ~35GB of game files, refusing to use your existing game files from Steam (error validating files).

Perhaps you think that that’s silly, and would like a way to not have to download everything again.

You’re in luck.

Quick disclaimer: I can’t guarantee that this will work for you, but it worked for me. If you’re reading this in the far future then this method may also become outdated and no longer work.  ¯\_(ツ)_/¯

1. Start the Rainbow Six Siege download on Uplay. Pause the download a minute in, after the file structure has been created. Navigate to the game’s location on Uplay and check that the files are indeed there (see step 3), then cancel the download. (You probably only need to get the directory itself made here, but better safe than sorry if you can wait the full minute)
2. Quit Uplay.
3. Copy the Siege game files from Steam into the folder where Uplay installs the game. For example, my Uplay installation puts the game’s files in this location:You need to put Steam’s copy of the game files in the “actual” game location, not where Uplay’s download-in-progress is going on – these are two different locations, with the download-in-progress being located within the game’s “normal” location.
4. Delete the STATE file in the Uplay game directory (1KB file)
5. Delete the Uplay download-in-progress folder, which is located in the Siege folder. The name should be fairly straightforward, but I don’t have a screenshot since I’ve already previously deleted the folder.
6. Start Uplay, and tell it to once again download Siege.
7. If everything’s working properly, it should start “Discovering files”. This may take a few minutes to get through, but it’ll still be a lot faster than downloading everything from scratch.
8. After it finishes discovering files, you’ll have to download a small amount of files. In my case, the download was around 150MB.
9. You’ll now have a working copy of the game on Uplay! Hopefully this helps a few of you who were in a similar situation to me.

Notes:

• According to the comments, this process can also work for other Uplay games (including The Division and Far Cry 5), so it might be valid for all Ubisoft games that use the same kind of install process.
• Renown and unlocks (including Operators) are saved, at least when I went from Free Weekend to Standard.
• Loadouts are reset: you retain access to anything which you’ve already unlocked but will have to re-equip them (scopes, alternative weapons etc).
• Situation progress is reset: You’ll keep any Renown / XP gained and will not gain any duplicate rewards for completing previously-completed mission objectives, but you’ll be back at Situation #1 with no displayed stars. Again: you do not gain Renown bonuses for completing any objectives which you already previously completed – the rewards are as if you had your previous progress saved.
• If you’re trying to go from Uplay Free Weekend to Steam Full Copy, apparently that’s much easier to do. According to my research: you basically repeat the above process but swap Uplay and Steam around. Steam doesn’t need a separate download directory and STATE files, so you can ignore those steps. Steam should automagically discover the files without any special help on your end.
• Dog has noted in the comments that you could also try this alternative method.