Unable to Recover Files After Restoring Encrypted Folder from ZIP Backup (Android)

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Hi everyone,

I’m looking for help because I’m worried I may lose access to my files.

What I did

  • I created a vault using the Android version of Cryptomator.

  • My files were encrypted normally, and I can see the encrypted .c9r files.

  • To back up the vault, I compressed one of the encrypted folders (for example, Zr6oudf...) into a password-protected ZIP archive.

  • I uploaded the ZIP file to cloud storage.

What happened

Later, I downloaded the ZIP archive, extracted it, and copied the encrypted folder back into the vault.

However, Cryptomator no longer recognizes the files.

Additional testing

To verify the issue, I exported my vault configuration and used the same vault key with the Cryptomator CLI/decryptor to decrypt one of the .c9r files.

Instead of decrypting, I received the following error:

“File was not encrypted using ‘’ vault.”

This is confusing because:

  • I have not changed the vault.

  • I have not changed the masterkey or key files.

  • I have not recreated the vault.

  • Everything happened within the same day.

  • Updating the application did not change the behavior.

My questions

  1. Is there any reason Cryptomator would report that a .c9r file belongs to a different vault even though it came from this vault?

  2. Could compressing the encrypted folder into a password-protected ZIP have altered anything?

  3. Is there any way to verify whether the encrypted files are still intact?

  4. Are there any recovery options before I assume the data is lost?

I’m happy to provide additional information if needed, such as:

  • Cryptomator version

  • Android version

  • Vault format/version

  • Screenshots of the error

  • Folder structure (without exposing sensitive information)

I would really appreciate any guidance. Thank you.