Desktop Client cannot synchronize Team folders with Advanced Permissions (Read-only ACL)

[thanasak2808]

Steps to reproduce

1. Install Nextcloud Hub 26 Spring (Server 34.0.1).
2. Enable the Team folders app.
3. Create a Team Folder.
4. Enable Advanced Permissions.
5. Upload one or more files into the Team Folder.
6. Assign a user with the following permissions:
   • ✅ Read
   • ❌ Create
   • ❌ Write
   • ❌ Delete
   • ❌ Share
7. Login with the Windows Desktop Client.
8. Start synchronization.

Expected behaviour

The Desktop Client should synchronize the existing files to the local computer in read-only mode.

The user should be able to:

• Browse folders
• Download files
• Synchronize files locally

The user should not be able to:

• Upload files
• Modify files
• Delete files

Actual behaviour

The user can access the Team Folder normally through the Web interface.

• Folder is visible.
• Files are visible.
• Files can be opened and downloaded from the browser.

However, the Desktop Client does not synchronize any files.

The client reports:

WindowsError5: Access is denied.

No files are downloaded to the local synchronized folder.

Workaround

Grant Write permission.

Permissions:

• ✅ Read
• ✅ Write
• ❌ Create
• ❌ Delete
• ❌ Share

After enabling Write, synchronization starts immediately without any other configuration changes.

Server configuration

Operating system: Linux 7.0.0-27-generic x86_64

Database: mysql 11.3.2

PHP version: 8.5.8

Nextcloud version: Nextcloud Hub 26 Spring (34.0.1)

Team folders version: 22.0.2

Updated from an older Nextcloud/ownCloud or fresh install: Fresh Install

Are you using encryption: no

Are you using an external user-backend, if yes which one: ActiveDirectory

Client configuration

Browser: Chrome, Firefox

Operating system: Windows 11 Home Single Language 25H2

Nextcloud Desktop Client: 33.0.7

Logs

Nextcloud Desktop Client:

WindowsError5: Access is denied.

Additional information

This issue only occurs when Advanced Permissions are enabled.

With Read-only permission:

Access Method	Result
Web UI	✅ Works
File download via Web	✅ Works
Desktop synchronization	❌ Fails

After granting Write permission:

Access Method	Result
Desktop synchronization	✅ Works immediately

The issue appears to be related to the interaction between Team folders Advanced Permissions and the Desktop Client synchronization process.

According to the expected ACL behavior, users with Read permission should be able to synchronize existing files locally in read-only mode without requiring Write permission.

Web server error log

No relevant errors were found in the server log during synchronization.

Client log

The Desktop Client reports:

WindowsError5: Access is denied.

[icewind1991]

This seems like an issue with the desktop client and not the groupfolders app.