Floccus: Launching browser results in Sync Fail; "waking up" the NextCloud Server solves the issue

[sproggit]

Describe the bug

Launching my (FireFox) web browser, I see that I get the little red square with a sync failure being reported. Nothing I try browser-side makes a difference. However, if I then navigate - using the same browser - to my local NextCloud instance where I have the NextCloud "Bookmarks" app installed... I can then return to the browser, click on the "Sync Now" button and everything works perfectly. It is like the server "goes to sleep" and this somehow throws the Floccus plug-in.

To Reproduce

Steps to reproduce the behavior:

1. Launch Browser
2. Wait for Floccus to attempt initial replication
3. Observe replication failure
4. Navigate to NextCloud instance where Bookmark Back End is located
5. Go back to Floccus in the browser and click "Sync Now" Observe that replication works.

Expected behavior

Ideally, it would be nice if the browser could find a way to "wake up" the server if it really is an idle server that causes the problem. If it isn't that, then maybe allow for the Floccus client to re-try every 5 minutes or so, maybe throwing up an error if there is no change after 3 attempts.

Screenshots

Happy to provide if needed, but doubt it will be necessary...

Desktop

(please complete the following information)

• OS: GNU/Linux Mint, 20.1; also seen on Windows 10 and earlier versions of Linux Mint
• Firefox
• Browser Version: 87.0, 64-bit
• Floccus version: v4.6.1
• Floccus sync method: NextCloud... not sure what the difference is between NextCloud Legacy and NextCloud Folders

Server

(please complete the following information)

• Raspbian (Raspberry Pi 4B with 4Gb RAM): Linux 4.19.75-v7l+armv7l Kernel
• Nextcloud version: 19.0.9
• PHP Version 7.3.27
• MySQL Version 10.3.23
• Bookmarks app version: 3.4.9

Note: Please write down the actual version numbers instead of writing 'latest'.

Debug log

It is often useful to provide a debug log file along with the issue. You can obtain a debug log of the most recent sync runs by clicking 'Debug log' in the bottom right corner of the floccus panel in your browser.

Note: As your debug log usually contains large parts of your bookmark data, instead of attaching it publicly to the issue here, I recommend uploading it privately at the following URL https://cloud.marcelklehr.de/s/PCi3iLWrzdMZSmw

• [Yes ] Debug log provided - floccus-4.6.1-2021-04-05.log - Uploaded April 5th @ 15:44 British Summer Time
• [ ]

Additional context

Tried all the usual... I upgraded all software components... The single weirdest thing is that this fails out-of-the-box, but if you navigate to the NextCloud instance and re-try, it works. It is like it is getting a timeout of some kind and the client just goes to a soft fail.

[sproggit]

Rather embarrassingly, I think I just spotted the issue...
The certificate for the site hosting my NextCloud instance had expired... By accessing the site with my browser and "accepting" the expired certificate, I was allowing the browser to trust it. The reason that Floccus was reporting an error was that it was unable to get a safe handshake with the server. New cert resolved the issue.