Android App Won't Launch / Freezes When CalDAV Server Unavailable

[mwaterbu]

Your Environment

• Version used: 21.0 apk (from Play Store)
• Operating System and version: Android 12

Expected Behavior

App launches and is usable

Current Behavior

App will sit on loading screen for several minutes. It may eventually show the task list but is unresponsive and shows an error at the bottom of the screen:

Unknown Sync Error: Error: Invalid response: -3
Network Error

Steps to Reproduce (for bugs)

1. Setup a CalDav server on local network
2. Connect one or more projects to this server
3. Disconnect from local network, but retain internet connectivity (don't go offline)
4. Attempt to launch app

Can you reproduce this reliably?

This can be reliably reproduced. When offline completely, the app launches without issue. However, if there is a network connection where the CalDAV server is not available (example listed above), this bug will occur.

[github-actions]

Thank you very much for opening up this issue! I am currently a bit overwhelmed by the many requests that arrive each week, so please forgive me, if I fail to respond personally. I am still very likely to at least skim read your request and I'll probably try to fix all (real) bugs if possible and I will likely review every single PR being made (please, give me a heads up if you intent to do so) and I will try to work on popular requests (please upvote via thumbs up on the original issue) whenever possible, but trying to respond to every single issue over the last years has been kind of draining and I need to adjust my approach for this project to remain fun for me and to make any progress with actually coding new stuff. Thanks for your understanding!

[github-actions]

Hello there mwaterbu! 👋

Thank you and congratulations 🎉 for opening your very first issue in this project! 💖

In case you want to claim this issue, please comment down below! We will try to get back to you as soon as we can. 👀

For more open ended discussions and/or specific questions, please visit the discussions page. 💖

[mwaterbu]

I attempted to reproduce this by simply taking the server offline, and staying connected to my local network, and the error state did not occur. The same error still showed up though (which makes sense):

Unknown Sync Error: Error: Invalid response: -3
Network Error

It also did not occur when I connected to a different WiFi network. For some reason, it only happens when I am on LTE.

[github-actions]

This issue has not received any updates in 90 days. Please comment, if this still relevant!

[mwaterbu]

To close the loop on this: I found that this was actually caused by the WebDAV backup sync, and only happened when I was on cellular data, not WiFi (even networks other than my home WiFi). As a workaround, I found that if I set the server to the local domain (hostname) instead of the local IP address, the issue no longer occurred. So I think my carrier was just ignoring the connection requests instead of returning an error. Ideally, SP wouldn't even try to connect to WebDAV unless I was on my home network, but this would require a new setting and likely some app permissions.

[johannesjo]

Thank you very much for sharing!