net.readURI fails for some URLs

General
1

Hi,

I'm working on an ICAL importer, which is working without issues on one of my Silverbullet instances.
After copying everything needed to another instance (this one running on another machine and within docker) i'm facing some problems:

On the second instance the call returns "nil" and in the console I see an error:

[Client] Error while dispatching event service:ec20a1fb-4ade-4152-944e-5cdf7ea5fcc5 : Error: Offline

However, the same URI does work fine on the other machine. I even tried with curl within the docker container running silverbullet, and I get my expected results, so the container is NOT offline or restricted.

Here is an example URI:

using this call in silverbullet for testing:
${net.readURI("https://calendar.google.com/calendar/ical/9f58302fba7f5cbce4a43b977e971147ac4769a9fc4b8a4eac9db0f0e2e4f6c0%40group.calendar.google.com/private-83edec1883894a685384e6c8833effdc/basic.ics")}

It seems not to be a kind of authentication error, as the URI works from "anywhere" using a plain curl request...

And even more strange: Trying Other URLs do work fine on the same instance. Example:
https://www.schulferien.eu/downloads/ical4.php?land=1&type=1&year=2026

Any Ideas to find the root cause would are welcome.
Thanks a lot in advance!

Nico

2

This is weird, I just created a test page on my instance and put literally this in it:

${net.readURI("https://calendar.google.com/calendar/ical/9f58302fba7f5cbce4a43b977e971147ac4769a9fc4b8a4eac9db0f0e2e4f6c0%40group.calendar.google.com/private-83edec1883894a685384e6c8833effdc/basic.ics")}

and it renders just fine?

CleanShot 2026-07-28 at 10.08.28
CleanShot 2026-07-28 at 10.08.281592×1074 61.1 KB

3

Also my experience. On one of my machine it`s fine, also. But the other isn't. That is what I don't understand.

The differences:
WORKING:
Host is a Windows Machine running the silverbullet exe locally.
(same good result on a new ramped up local silverbullet testserver on a Linux client as well)

NON-WORKING:
Host is a linux server running docker with the latest image. It's behind a nginx reverse proxy.
The link you tried above doesn't work (returns nil) , while the other one (..."Schulferien"...) renders fine on the same machine.

So I wonder, if that has something to do with docker and/or the reverse proxy.
However, why is one URL working and the other not? Both are working if I try from within the docker container...

Scrolling through the developer console log, I see a "503 Bad Gateway" error, for the failing URL. But I don't see why and where this is coming from.