Failed to fetch an image or build from source: error building: unexpected EOF

Hi there, I’m new to Fly.io and this is the first app I’m deploying. When trying to deploy my Rails app I get the following error

Error failed to fetch an image or build from source: error building: unexpected EOF

I really have no clue what could be causing it so if someone could point me in the right direction that would be amazing. I tried running flyctl launch again and I got the below error:

This is an error connecting to our remote Docker builder. Will you run fly doctor and see if everything passes?

You can also try this experimental setting: fly wg websockets enable

That changes how we communicate with the Docker builder (it uses websockets instead of UDP). If you’re running a local firewall or VPN service, this can help prevent weird errors caused by conflicts.

Hi @kurt – I just encountered the same problem, and can confirm that enabling the websockets fixed it.

I’m not sure why it was happening originally, it worked fine last week but today I’ve had a lot of problems. Had to forcibly reset the wireguard connection for example.

Why not you told this in [URGENT] Contact Lost with instance - #12 by Samer, I died troubleshooting 100 times. :sweat_smile:

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thanks, it works, it seems my ISP drop udp connection.