Web UI won't load on localhost - Ubuntu 20.04

I converted my server this past weekend from 18.04 to 20.04 - I guess I like my LTS :slight_smile:

On the server, Duplicati is running fine:

administrator@Server:~$ sudo systemctl status duplicati
[sudo] password for administrator: 
● duplicati.service - Duplicati web-server
     Loaded: loaded (/lib/systemd/system/duplicati.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2020-06-20 05:38:38 EDT; 3 days ago
   Main PID: 1459 (mono)
      Tasks: 43 (limit: 18986)
     Memory: 8.2G
     CGroup: /system.slice/duplicati.service
             └─1459 DuplicatiServer /usr/lib/duplicati/Duplicati.Server.exe

Jun 20 05:38:38 Server systemd[1]: Started Duplicati web-server.

And so it appears to be on the desktop that I upgraded yesterday:

david@david-desktop:~$ systemctl status duplicati
● duplicati.service - Duplicati web-server
     Loaded: loaded (/lib/systemd/system/duplicati.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2020-06-24 02:52:16 EDT; 2min 27s ago
   Main PID: 1808 (mono)
      Tasks: 10 (limit: 38069)
     Memory: 209.5M
     CGroup: /system.slice/duplicati.service
             └─1808 DuplicatiServer /usr/lib/duplicati/Duplicati.Server.exe

Jun 24 02:52:16 david-desktop systemd[1]: Started Duplicati web-server.

BUT here’s the problem: the Web UI loads fine from the server, but at my desktop, using “localhost” in the same browser, it will not load. The browser (Firefox) just hangs. And yes, netstat says I have that process listening on 8200 as it should be.


Can you try a different browser, just to make sure it isn’t Firefox?

I will freely admit I rolled my eyes at this suggestion when I saw it. But I installed Midori and damn if my local web UI didn’t load right up.

I will do some cache-clearing and plugin-disabling and the rest of it to try to isolate the issue. Thanks.

Damndest thing, however: that the remote server still loads in FF.

Do you often run two Duplicati in one browser? That scenario behaves poorly for me, but usually error is:

however my PC has multiple Duplicati (server side as well, not just browser), so might be rather unusual.
I suppose I could add an issue to the backlog or try to investigate. Mentioning this in case yours is related.

I look at two Duplicati instances in one browser yes. This was NEVER a problem until I upgraded the local system to 20.04. The remote system was upgraded a week earlier.

I have Duplicati running as a service on both.

This problem showed up in FireFox but did not replicate when I installed Midori.

The httpserver is technically a different GitHub project by the same original author. Current Duplicati maintainers might not know it well, but the hang isn’t clearly in httpserver. It’s an integrated system…

Probably needs to be narrowed down with Firefox Web Developer menu. Maybe an expert can help.

Below is also a good idea but I don’t know how far it got. This definitely seems like it needs isolation.

Although the two-Duplicati theory is weakening, does Midori do two, and can Firefox do one? Simplify…

Getting some sort of network activity trace from Firefox would help. I’m not very expert at that, but if you prefer to watch network with tcpdump, tshark, or wireshark, I can probably help you with basic testing…

Since Midori is working, you could go in and run About --> Show log --> Live --> Profiling to see if Firefox trying to connect causes any visible activity at all. That’s a little easier for a one-shot than using a log file.

It is definitely doing two without issue in Midori. And FireFox does one just fine - but only the remote server. Localhost still hangs.

Nothing visible on any setting in Show log --> Live --> Profiling when I try to connect from FireFox

Maybe some network captures within my localhost are in order.

How about trying Firefox in Safe Mode, just to see if it’s a possible interaction with some oddball extension.

I don’t know if that was a comment or a how-to question, but the most likely preinstalled tool is tcpdump.

tcpdump -i any port 8200 (and plenty more options exist for later, if traffic even starts getting going)

Wireshark might need to be installed, but has Analyze --> Follow --> TCP Stream which eases reading.

Easiest way to get an overview is Firefox --> Web Developer --> Network, but I’m not sure it has details.

One nice thing about it is it won’t be bothered by encryption (is this HTTP, or did you set up encryption?).

This is HTTP. So yeah.

Not sure when I will get to this but I will post.