Second device setup fails on Linux: dc_database_backup.sqlite timed out during import

[Otzie2023]

• Operating System (Linux/Mac/Windows/iOS/Android):
  Linux (Desktop), Android (primary device)

• Delta Chat Version:
  Desktop: v2.35.0 (Snap-Package)
  Android: v2.35.0 (Playstore)

• Expected behavior:
  Adding the desktop client as a second device should complete successfully
  and import the existing profile including chats and key material.

• Actual behavior:
  Adding the desktop client as a second device fails every time.
  The import aborts during transfer/unpacking of the backup with a timeout.

  Error messages include:
  dc_database_backup.sqlite: connection lost: timed out
  as well as:
  Failed to import backup from QUIC stream
Failed to unpack

• Steps to reproduce the problem:

  1. Delta Chat is set up on Android as the primary device
  2. Install Delta Chat Desktop (first Flatpak, then Snap for testing)
  3. On desktop, choose “Add as second device”
  4. Scan the QR code with the Android device
  5. Transfer starts
  6. Process reproducibly fails with a timeout while unpacking the database

• Screenshots:
  Screenshot of the error message available (can be attached)

• Logs:
  Desktop logs contain:

  • Failed to import backup from QUIC stream
  • failed to unpack dc_database_backup.sqlite
  • connection lost: timed out

  The issue occurs regardless of the packaging format:

  • reproducible with Flatpak
  • reproducible with Snap

  Additional notes:

  • Both devices are on the same network
  • No VPN or proxy in use
  • Firewall temporarily disabled for testing
  • USB tethering tested as well
  • Issue remains reproducible

[nicodh]

Since the behaviour is not reproducable for others could you investigate a bit:

Create a new account on Android, start some chat and then try to add desktop as second device to that new account. Works?

Ceate a backup of the affected account and use that to recover the account on desktop? Then we should at least be able to see if it is a network issue (what I don't expect) or something else.

It is even possible to restore the account from backup on the same device (Android) (resulting in having 2 identical accounts) and then test the add second device there

[Otzie2023]

I just created a completely new user on Android and tried to log them in on my computer as a secondary user, but without success (see attachment). It is important to note that
the account I originally tried to synchronize with my computer as a secondary account may have been created on the computer originally, and my phone is the secondary device. Since I completely reset my system, this status was also gone from Delta Chat Desktop. This did not affect my phone, however.

So, in the current test, I created a completely new account on my phone and tried to add my computer as a second device via QR code. You can find the entire log (from the phone) in the attachment.

deltachat-log-20260215-202842.txt

[WofWca]

The error path is as such:

https://github.com/chatmail/core/blob/cf5b145ce0354ed8832917847d374e38bffc708c/src/imex/transfer.rs#L327-L329

https://github.com/chatmail/core/blob/0defa117a0a302985c61fe211d1a6a948a06d4f6/src/imex.rs#L344-L346

Tar reader starts to unpack the files from the Tar stream that is being transferred overt the network, but the stream gets interrupted.

i.e. I suspect that there is some network error.

Have you tried transferring over a hotspot? Either set up on the laptop or the phone.

Also, this issue is not specific to DC Desktop.

[Otzie2023]

No, both devices were connected to the LAN via a Fritzbox (router). My mobile phone was connected to the Wi-Fi and the desktop was connected via LAN. About a year ago, this didn't cause any problems. Transfer via a hotspot network would not be possible because the email and DNS servers would not be accessible, as they only work on my router's LAN.

[WofWca]

Transfer via a hotspot network would not be possible because the email and DNS servers would not be accessible

They do not need to be accessible. The backup transfer process does not involve WAN network activity.

[Otzie2023]

I tried exporting via backup file. However, I couldn't figure out where the file was saved. See screenshots in the attachment.

[WofWca]

It's supposed to be just the regular "Downloads" folder.

[Otzie2023]

Transferring files works without any problems.

[WofWca]

Are you willing to try it with a hotspot, or a different router? Otherwise I'm not sure what we can do with this issue.

[Otzie2023]

I already tried that with another router, and got exactly the same error.