# Error message in browser - "The host header sent by the client is not allowed"

**URL:** <https://forum.duplicati.com/t/error-message-in-browser-the-host-header-sent-by-the-client-is-not-allowed/5806>\
**Category:** Support\
**Created:** [December 29, 2018, 1:39am UTC](https://forum.duplicati.com/t/error-message-in-browser-the-host-header-sent-by-the-client-is-not-allowed/5806 "2018-12-29T01:39:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![pcgeek86](https://forum.duplicati.com/user_avatar/forum.duplicati.com/pcgeek86/32/2478_2.png) [@pcgeek86](https://forum.duplicati.com/u/pcgeek86)\
**Post date:** [December 29, 2018, 1:39am UTC](https://forum.duplicati.com/t/error-message-in-browser-the-host-header-sent-by-the-client-is-not-allowed/5806/1 "2018-12-29T01:39:20Z")

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Hello, I’m a first-time user of Duplicati.

I figured I would try to run it on one of my Raspberry Pi 3 B+ devices under a Docker container, for ease of portability. I’m planning to set up Duplicati with Backblaze for encrypted backups.

When I ran the Docker container, using the command line below, and opened the Duplicati endpoint in Google Chrome (running on Windows 10), I received the error message below.

> “The host header sent by the client is not allowed”

```plaintext
docker run -p 8200:8200 -v $(pwd)/duplicati:/app/duplicati duplicati/duplicati:linux-arm32v7-latest

```

Is there an environment variable that I need to set in the `docker run` command that maybe I’m missing? For now I just used the `docker run` command from the documentation on Docker Hub.

[https://hub.docker.com/r/duplicati/duplicati](https://hub.docker.com/r/duplicati/duplicati)

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<div class="post-metadata">

**Author:** ![drwtsn32](https://forum.duplicati.com/user_avatar/forum.duplicati.com/drwtsn32/32/2591_2.png) [@drwtsn32](https://forum.duplicati.com/u/drwtsn32)\
**Post date:** [December 29, 2018, 3:50am UTC](https://forum.duplicati.com/t/error-message-in-browser-the-host-header-sent-by-the-client-is-not-allowed/5806/2 "2018-12-29T03:50:22Z")

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Yeah this is caused by additions to Duplicati to help protect against DNS-based attacks.

Try accessing the Duplicati UI using its IP address instead of a hostname. You can add the hostname to the appropriate area of the settings section to enable access by hostname.

More info here:

> [@Duplicati upgrade - "The host header sent by the client is not allowed"](https://forum.duplicati.com/t/duplicati-upgrade-the-host-header-sent-by-the-client-is-not-allowed/5302):
>
> Hi there, I’m probably missing something really obvious here - I just upgraded from 2.0.3.3 to 2.0.4.4 but I now cannot log in remotely. The GUI loads and the process is listening on 0.0.0.0:8200 to remote access is still enabled from the earlier configuration - but somehow I cannot now load the login page. I saw reference to this issue on a thread for the release notes to an earlier version, but I cannot work out how to apply the described fix (set hosts to \*, or preferably use the full hostn…