Error E020 while trying to synchronize Ungoogled Chromium v139.0.7258.66 to Linkwarden v2.13.1 with Floccus v5.7.0

[Leiasticot]

Which version of floccus are you using?

5.7.0

How many bookmarks do you have, roughly?

50

Are you using other means to sync bookmarks in parallel to floccus?

No

Sync method

Linkwarden

Which browser are you using? In case you are using the phone App, specify the Android or iOS version and device please.

Ungoogled Chromium v139.0.7258.66

Which version of Nextcloud Bookmarks are you using? (if relevant)

Linkwarden v2.13.1

Which version of Nextcloud? (if relevant)

No response

What kind of WebDAV server are you using? (if relevant)

No response

Describe the Bug

The error :
E020: Could not parse server response. Is the bookmarks app installed on your server? Unexpected token '<', " "... is not valid JSON

happens when I try to synchronize to my Linkwarden selfhosted instance.

floccus-5.7.0-2025-11-13-full.log

Expected Behavior

The synchronisation to works

To Reproduce

Install Linkwarden using docker accessible with a wireguard VPN on a mini-pc.
Client W11 using ungoogled chromium with wireguard VPN on (I can access to linkwarden).
Nginx Proxy Manager reverse proxy (using a wildcard certificate) with adguard home for split DNS.
My computer can access to Linkwarden using the subdomain.domain even on https://subdomain.domain/api/v1/search
Try to synchronize from local bookmarks to Linkwarden : not ok
Tried to uninstall/reinstall : not ok

Thanks you very much !

Debug log provided

• I have provided a debug log file

[github-actions]

Hello! 👋

Thank you for taking the time to open this issue with floccus. I know it's frustrating when software causes problems. You have made the right choice to come here and open an issue to make sure your problem gets looked at and if possible solved. Let me give you a short introduction on what to expect from this issue tracker to avoid misunderstandings. I'm Marcel. I created floccus a few years ago, and have been maintaining it since. I currently work for Nextcloud which leaves me with less time for side projects like this one than I used to have. I still try to answer all issues and if possible fix all bugs here, but it sometimes takes a while until I get to it. Until then, please be patient. It helps when you stick around to answer follow up questions I may have, as very few bugs can be fixed directly from the first bug report, without any interaction. If information is missing in your bug report and the issue cannot be solved without it, I will have to close the issue after a while. Note also that GitHub in general is a place where people meet to make software better together. Nobody here is under any obligation to help you, solve your problems or deliver on any expectations or demands you may have, but if enough people come together we can collaborate to make this software better. For everyone. Thus, if you can, you could also have a look at other issues to see whether you can help other people with your knowledge and experience. If you have coding experience it would also be awesome if you could step up to dive into the code and try to fix the odd bug yourself. Everyone will be thankful for extra helping hands! If you cannot lend a helping hand, to continue the development and maintenance of this project in a sustainable way, I ask that you donate to the project when opening an issue (or at least once your issue is solved), if you're not a donor already. You can find donation options at https://floccus.org/donate/. Thank you!

One last word: If you feel, at any point, like you need to vent, this is not the place for it; you can go to the Nextcloud forum, to twitter or somewhere else. But this is a technical issue tracker, so please make sure to focus on the tech and keep your opinions to yourself.

Thank you for reading through this primer. I look forward to working with you on this issue! Cheers! 💙

[marcelklehr]

Hi @Leiasticot
Thank you for taking the time to give feedback by opening this issue. I'll try to help troubleshoot as best I can.
I sadly cannot reproduce this with the official instance of cloud.linkwarden.app.
When I try to access the URL in the logs I get a HTML page that says "Welcome to your SWAG instance", which might be what floccus gets. Could it be you have made a mistake in your setup?