Android: NullPointerException opening Nextcloud offline vault

[dhcgn]

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Summary

When trying to open an existing vault that resides in a Nextcloud-managed local folder marked as “Available offline,” the Android app accepts the password but immediately shows the generic error “Ein Fehler ist aufgetreten.” The logs consistently show a NullPointerException in DocumentsContract.buildChildDocumentsUriUsingTree(...)-

System Setup

- Android: android 16 / API36 using
- Cryptomator: v1.12.2 (3020) "Google Play Edition"

Cloud Type

Local storage

Steps to Reproduce

1. On Android, open Cryptomator 1.12.2.
2. Choose Open existing vault and navigate via the Android file picker to a local folder managed by the Nextcloud app that is marked Available offline.
3. Select the vault folder (the folder contains masterkey.cryptomator and vault.cryptomator).
4. Enter the correct vault password and confirm.
5. Cryptomator attempts to unlock and list the vault root.
6. Error “Ein Fehler ist aufgetreten.” occurs

Expected Behavior

After entering the correct password, the vault should unlock and its root directory should be listed, allowing normal file browsing.

Actual Behavior

After entering the password, Cryptomator shows the generic message “Ein Fehler ist aufgetreten” and fails to display the vault contents. The logs show an NPE in DocumentsContract.buildChildDocumentsUriUsingTree(...) within the Local/SAF content repository path. The issue reproduces reliably. Using the app’s WebDAV integration to open the same folder as a remote vault works without errors.

Reproducibility

Always

Relevant Log Output

ErrorCode: OGQC:CEV0  
W 20251018102622.063 Message Ein Fehler ist aufgetreten

E 20251018102622.057 ExceptionHandler java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getAuthority()' on a null object reference
    at android.provider.DocumentsContract.buildChildDocumentsUriUsingTree(DocumentsContract.java:1067)
    at org.cryptomator.data.cloud.local.LocalStorageAccessFrameworkImpl.list(LocalStorageAccessFrameworkImpl.kt:168)
    at org.cryptomator.data.cloud.local.LocalStorageAccessFrameworkContentRepository.list(LocalStorageAccessFrameworkContentRepository.kt:54)
    at org.cryptomator.data.repository.DispatchingCloudContentRepository.list(DispatchingCloudContentRepository.kt:103)
    at org.cryptomator.data.cloud.crypto.CryptoImplVaultFormat7.list(CryptoImplVaultFormat7.kt:151)
    ...

I 20251018102347.953 App Cryptomator v1.12.2 (3020) "Google Play Edition" started on android 16 / API36 using a SM-S938B

(Repeats at 10:26:29, 10:38:46, 10:39:19, 10:40:52, 10:40:55, 10:52:39, 10:52:54 with the same stack and `OGQC:CEV0`.)

Anything else?

• Workaround: Opening the same vault via WebDAV within Cryptomator works as expected (no errors), indicating the vault data is fine and the issue affects the Local/SAF access path (likely interaction with Nextcloud’s DocumentProvider when folder is set to “Available offline”).
• Log.txt