Invalid Masterkey - There is an error with your masterkey. Please ask us for support!

Hello and thx for helping.

I just swiched from an iPhone 6 to an iPhone 7 and I’m receiving this error on both of my phones (see topic). On the iPhone 6 I hat TouchID which does not work anymore, on the iPhone 7 I was never able to open my Vault. However, I’m useing the same Vault from Mac Book Pro, Mac Mini and Windows 10 OS. Only the iOS Versions seam to be affected from this error.

I’m using Dropbox.
iOS 11.1
Cryptomator: 1.2.6 (488)

This particular error message happens when the iOS app is unable to parse the JSON content of the masterkey file. Fyi, JSON is something like this:

  "key": "value"

But it’s strange that you can actually unlock the vault on other operating systems. Perhaps the JSON parser in Java handles it differently.

Could you please make a copy of the masterkey file, edit it with e.g. TextEdit and redact the contents of primaryMasterKey, hmacMasterKey, and versionMac? You can either post the redacted file here or send it to

thank you Tobi for the super fast reply.
I sent you my file via email. That content does not look like a valid JSON format.

I changed my masterkey file with a text editor by removing rubish at the end of file (looked like a HTTP response from IIS ?!) This solved my problem. After syning with my iPhone, I can open my Vault again.

Thanks for your support!

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