Image thumbnails won't load on Android Zulip app when reverse proxied through Cloudflare

[recklessnl]

Similar to #4102, I am selfhosting Zulip on a small server. I use Caddy as the reverse proxy and run it through Cloudflare (free service). It all works fine, including mobile notifications, but the problem is that on mobile only, the image thumbnails do not load. This means I cannot see the profile images in any thread, nor GIFs that are previewed from an URL. It works just fine from any browser or the desktop apps - it's specifically the mobile that does not load the image thumbnails or previews.

I'm suspecting Cloudflare is the issue for some reason as the previous thread I linked mentioned that being the problem. A solution was never offered however, so I cannot be too sure.

Any ideas on how to troubleshoot and fix this?

[gnprice]

Thanks for the report.

It sounds like the pattern of your symptoms is:

• Images don't show up within the message list: neither the avatars of message senders, nor image previews within messages.
• Images do show up just fine elsewhere in the app, including the lightbox (as you mentioned at iOS and Android app won't show uploaded image thumbnails #4102 (comment) that they show up fine after you click on them) and the profile screen (ditto).

Given that, I suspect your symptoms have the same root cause as #5797, described here: #5797 (comment)

If that's right, then this is an issue that's fixed by our upcoming new app, written in Flutter. The Flutter app reached beta in December:
https://chat.zulip.org/#narrow/stream/2-general/topic/Flutter/near/1708728

So one debugging step that would be helpful is for you to try out that beta and see if the issue goes away. If so, that'd confirm the diagnosis; if it doesn't, we can debug further.

[recklessnl]

Hi Greg, thanks for the reply. I just installed the Flutter-based beta that you linked on my Android device and just as you suspected, images load just fine on this beta. The app feels very snappy too I might add, albeit a bit sparse at the moment (definitely missing the edit message feature and a dark mode). Do notifications work with the beta too? And since this beta will eventually be the default Zulip app, do you want to further debug this issue or close it? Thanks for the help.

[gnprice]

Great! Thanks for confirming.

The app feels very snappy too I might add, albeit a bit sparse at the moment (definitely missing the edit message feature and a dark mode). Do notifications work with the beta too?

Thanks! Yeah, I also appreciate how much snappier it feels. Partly we've made some better choices in the new app vs. the old, but a big factor is that Flutter is just a better platform to build an app with than React Native.

And indeed, the beta app already has notifications too. Feedback welcome (on GitHub for zulip-flutter, or on chat.zulip.org in #mobile); some features of notifications are still to be implemented, and there are probably also bugs we don't yet know about.

Those other two features are tracked as:

• compose: Support editing an already-sent message zulip-flutter#126
• ui: Implement dark theme zulip-flutter#95

And since this beta will eventually be the default Zulip app, do you want to further debug this issue or close it?

I'll leave this issue open, since it is a real issue in this repository's app. When the new app approaches being ready to replace this one, we'll migrate over from here the issues that still apply to the new app, and then after the replacement is complete we'll archive this repo wholesale, including all its remaining issues.