[Bug]: Permission denied when syncing Android app backups on self-hosted Nextcloud to desktop

[pflavio]

⚠️ Before submitting, please verify the following: ⚠️

• [x] This is a bug, not a question or a configuration issue.
• [x] This issue is not already reported on Github (I've searched it).
• [x] Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• [x] I agree to follow Nextcloud's Code of Conduct

Bug description

I'm on Linux using Nextcloud desktop client 3.14.1 and on Android using 3.29.2.

I'm using Nextcloud to back up data from Android apps such as Signal and Aegis. On the phone, I have no issues. On the web client it's also fine. I can upload and access the data. Now on the desktop client I get a "Permission denied" error whenever a new backup from an app was uploaded to Nextcloud. I can however see the data in the Dolphin folders and also interact with them. I even set permissions to 777 for those specific folders to see if it helps but no luck.

Steps to reproduce

1. In an Android app, toggle backups and select a folder on my self hosted Nextcloud instance as destination
2. Perform backup without issues. Verify it on Nextcloud for Android or the web interface.
3. Switch to Linux desktop and wait for Nextcloud desktop to detect changes on Nextcloud
4. Nextcloud desktop starts syncing and will show a "Permission denied" error for every new file from the backup

Expected behavior

Syncing should work regardless of where data is accessed

Which files are affected by this bug

signal-2024-11-09-03-57-02.backup .backup56d5e56d-454e-4994-b9af-d71ff4ddf5d8.tmp

Operating system

Linux

Which version of the operating system you are running.

Linux 6.11.6-arch1-1

Package

Community FlatPak

Nextcloud Server version

30.0.2

Nextcloud Desktop Client version

3.14.1

Is this bug present after an update or on a fresh install?

Updated from a minor version (ex. 3.4.2 to 3.4.4)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

Are you using an external user-backend?

• [x] Default internal user-backend
• [ ] LDAP/ Active Directory
• [ ] SSO - SAML
• [ ] Other

Nextcloud Server logs

Additional info

Nextcloud Android 3.29.2