Traefik host error: unexpected number of parameters

The Traefik Host configuration now only accepts one domain per host. Here is the updated and working syntax.

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By. Jacob

Jacob Kristensen (Turbulentarius) is a Web Developer based in Denmark. He is currently pursuing a Bachelor's degree in Web Development at Zealand, focusing on learning React and refining his existing skills.

Edited: 2025-08-29 17:19

After moving to Traefik 3+ I got the following strange error in my log:

error while parsing rule Host(`beamtic.com`, `beamtic.net`... unexpected number of parameters; got 4, expected one of [1]

This error is apparently caused by Traefik 3+ having changed the syntax for multiple hosts to only one domain for each host(). After updating my label with the correct syntax it started working again.

Simply separate each Host() with Logical OR || (two pipe characters):

traefik.http.routers.beamtic-services-secure.rule: Host(`beamtic.com`) || Host(`beamtic.dk`)

I was unaware I needed to make changes to my configuration, not least because the officially linked migration page had seemingly been removed from the Traefik documentation.

Of course, in general you should never remove articles from your website without redirecting to replacement material, and in this case at least it seems the 404'ed article is still needed to inform us about such changes.