Traefik can't connect to dockersocket after upgrade to traefik V3.6.0

[rama31244]

Not sure if this is a traefik issue or a dockersocket issue but traefik stops working after upgrade to v3.6.0 with the following error

2025-11-14T18:33:37+11:00 ERR Failed to create Docker API client error="unable to parse docker host `dockersocket`" providerName=docker
2025-11-14T18:33:37+11:00 ERR Provider error, retrying in 1.915221863s error="unable to parse docker host `dockersocket`" providerName=docker

[ansgaross]

Came here to see if there was a resolution for this. There was not, so I did some trial and error.

It's a Traefik issue / feature.

This started with v3.6.1 for me. Possibly related to bug fix "[docker] Auto-negotiate Docker API Version (#12256 by felixbuenemann)"

In any case, changing the environment variable DOCKER_HOST in my Traefik container from 'dockersocket' to 'tcp://dockersocket:2375' fixed this for me.

Then I removed that environment variable altogether and it still worked, since I already had this in my traefik.yml:

providers:
  docker:
    endpoint: "tcp://dockersocket:2375"

Hope that helps!

[rama31244]

Amazing! Completely fixed the issue. Thank you so much!

[mmartial]

Update: confirming that it works when doing both of the following

1. use tcp://dockersocker:2375 in the traefik.yaml file
2. removing the DOCKER_HOST entry from the Traefik template

[zaggash]

I think this is explained here.
https://github.com/wollomatic/socket-proxy?tab=readme-ov-file#usage-with-traefik--21131---361