[Bug]: Syncing encrypted files (E2E) with Linux client failes after reboot

[JoachimClemens]

⚠️ Before submitting, please verify the following: ⚠️

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

Bug description

I’ve an issue with the Nextcloud desktop client for Linux in combination with E2E encryption. After setting sync and encryption up, everything works fine. But after each reboot, the client fails to sync the encrypted files. I get the following error:

“The server was unable to complete your request. If this happens again, please send the technical details below to the server administrator. Error transferring https://[server]/remote.php/dav/files/[plain text filename] - server replied: Not found”

I have the same problem on both Linux machines that I use. I’m also using the Windows desktop client on another machine, and here everything works fine without any issues. The Linux clients also have no issues syncing unencrypted folders. When I disable and enable encryption, it often works again, but not always.

The Linux desktop client version is 3.14.2, the OS is Ubuntu 22.04. The server version is 29.0.8. Please let me know if you need additional information.

Steps to reproduce

With Linux desktop client:

1. Add an account
2. Add a folder sync connection
3. Set up E2E encryption
4. Mark encrypted folder for sync
5. Wait until all files are synced
6. Reboot

Expected behavior

Encrypted files should be synced correctly also after reboot.

Which files are affected by this bug

All files in encrypted folder

Operating system

Linux

Which version of the operating system you are running.

Ubuntu 22.04

Package

Official Linux AppImage

Nextcloud Server version

29.0.8

Nextcloud Desktop Client version

3.14.2

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

Fresh desktop client install

Are you using the Nextcloud Server Encryption module?

Encryption is Enabled

Are you using an external user-backend?

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

Nextcloud Server logs

Nothing present in the server log

Additional info

No response