Correct file to select when adding a vault (vault.cryptomator or masterkey.cryptomator)?

Hello Cryptomator Community!

I have a question—maybe a bit basic, but I hope it helps others too. In short: what’s the correct way to add a vault to Cryptomator’s vault list (on Windows, Linux, or Android)? When the app asks me to select a file, which of these should I choose?

  1. vault.cryptomator
  2. masterkey.cryptomator

From what I’ve read, vault.cryptomator contains the reference to where the key is stored—whether in the vault’s root directory or on external hardware.

On Android, the app lets me select either file, but on Windows, it prompts me to pick masterkey.cryptomator only if vault.cryptomator doesn’t exist (so I assume this applies to vaults created before version 8).

What happens if I accidentally select masterkey.cryptomator? Does it cause security risks or compatibility issues? Do I need to recreate the vault? I know recreating it is a drastic fix, but I’d love to hear your advice. Thanks so much for the help <3!