Attempting to sync with radicale results in "Remote end closed connection without response"

[lokesh-krishna]

• Vdirsyncer version: version 0.18.1.dev0+g3191886.d20211204
• Server software (and which version): radicale 3.1.7-1
• Python version: 3.10.4
• Operating system: Arch Linux
• Config file: config
• Error output:

  Syncing contacts/contacts-3e3ca063-d88c-4cd7-9141-69eb2ca57602
  Syncing calendars/calendars-655c997b-5938-499b-9348-e26bbaf26a85
  Syncing tasks/tasks-a2e77698-f5c0-4e17-98f1-b16ba78909bd
  error: The server returned something vdirsyncer doesn't understand. Error message: InvalidXMLResponse('Invalid XML encountered: no element found: line 1, column 0\nDouble-check the URLs in your config.')
  error: While this is most likely a serverside problem, the vdirsyncer devs are generally interested in such bugs. Please report it in the issue tracker at https://github.com/pimutils/vdirsyncer/issues
  error: Unknown error occurred for tasks/tasks-a2e77698-f5c0-4e17-98f1-b16ba78909bd: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))
  error: Use `-vdebug` to see the full traceback.
  error: Unknown error occurred for contacts/contacts-3e3ca063-d88c-4cd7-9141-69eb2ca57602: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))
  error: Use `-vdebug` to see the full traceback.
  error: 3 out of 6 tasks failed.

• Debug output: debug

[WhyNotHugo]

Looks like radicale closes the connection and then refuses all other connections.

Are you using any other client to talk to this radicale server (e.g.: are you sure it works okay?). How many concurrent connections does it support? What does the setup look like?

[lokesh-krishna]

Thanks for replying!

My setup is as follows: DecSyncCC on my Android device and then syncing the collections over to my laptop with Syncthing. On my laptop, I have Radicale running and vdirsyncer then pulls the collections from it and exposes it to a bunch of utilities (khal, khard and todoman).

I don't use any other clients with this Radicale server because it's a local server but I can access it from my browser and it does display my collections.

I'm not sure how many concurrent connections it supports and didn't know that was something I could configure so I'll look into it. Is there anything else I should be trying?

EDIT: Radicale has a default setting of a maximum of 20 connections. I just tried setting it to 100 and increasing the timeout from 30 to 300 but still get the exact same error upon running vdirsyncer sync.