Win10 "Unable to Connect"; OctoPrint Server won't autostart;

What is the problem?

Attempting to start the program results in a timeout and error screen "Unable to connect"
"Firefox can't establish a connection to the server at localhost:5000"

What did you already try to solve it?

Completely uninstalled program elements and installed latest version.

After much troubleshooting I found that the Octoprint server service was not running, even though it was configured to Autostart.

Manually starting the service allows the application to run normally.

Have you tried running in safe mode?

Can't do it. Program won't start.

Did running in safe mode solve the problem?


Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!) (17.3 KB)


Additional information about your setup

OctoPrint version - 1.9.3, OctoPi version (none), printer - Ender 3 S1, firmware - stock, most recent, browser - Firefox 122.0.1, operating system - Windows 10 22H2, Plugins - Bed Visualizer 1.1.1; File Check 2021.2.23; Firmware check plugin 2021.10.11 as much data as possible
Octoprint installed using jneill's installation package.

I'm not sure if this is a Windows problem or an Octoprint problem or an install package problem. As far as I can tell, the problem does not occur with any other application.


I see ip addresses in the logs. For testing, temporarily disable win 11 defender firewall.
Search "Firewall"
Click on "Firewall & network protection"

Click on "Domain Network"
Turn off the switch "MS Defender Firewall"
Click "Yes" on security screen.

Click back arrow in upper left.
Do the same for "Private Network" and "Public Network".

Test your app.

When done testing, go back to Firewall window click "Restore Setting" under Domain.
Give it a few seconds.
All three should be back on.

Good luck,

That did allow me to start the program while the firewall was off. But will that solve the issue for the next time I restart?

Today I booted up, went to the Services snapin and started the Octoprint service manually, but the UI couldn't connect even with the service running.
Apparently this is a firewall issue, but the OctoPrint service was enabled in the Firewall already.
Does anyone know the details of getting OctoPrint through the firewall when it is enabled?

By default windows "blocks" all non standard ports and most non standard servers.
You will have to tell the windows firewall you want to allow Octoprint all the time;

Search "Firewall"
Click on
Click on

Depending your network, select private. If don't work, select public on Octoprint.


I did that a long time ago. WinDefender shows it as allowed. I re-checked it just now.

I'll see what it does next time I reboot.