---
title: "TYPO3 Exception 1396795884"
manual: "TYPO3 Exceptions"
version: "main"
permalink: "https://docs.typo3.org/permalink/t3exceptions:typo3-exception-1396795884"
source: "Exceptions/1396795884.rst"
modified: "2026-09-16T07:39:08+00:00"
---

# TYPO3 Exception 1396795884

> [!NOTE]
> Below, the TYPO3 community may have provided additional information or
> solutions for this exception. However, these may or may not apply to your
> particular case. If you can provide more information, you should come back
> here and add your experience and solution steps to this issue once you have
> resolved it.
>
> General TYPO3 troubleshooting tips can be found in the *Troubleshooting*
> section in the menu. You can also ask questions and receive support in the
> [TYPO3 Questions category on talk.typo3.org](https://talk.typo3.org/c/typo3-questions/).
>
> To add your experience, click "Edit on GitHub" above and follow the
> ["Edit on GitHub" workflow](https://docs.typo3.org/m/typo3/docs-how-to-document/main/en-us/Howto/EditOnGithub.html#docs-contribute-github-method).
> Also check out
> [our tip on Coding Style and reST](https://docs.typo3.org/permalink/t3exceptions:tip-about-rest-coding-style).

## The current host header value does not match the configured trusted hosts pattern!

### Error displayed during installation of TYPO3

Usually, when installing a new TYPO3 instance, the system will detect
the instance has not been configured yet and will redirect to the
installer to proceed with the installation. However, depending on web
server configuration, this trusted hosts pattern error may still be
thrown and the redirect will not be performed. An easy way to circumvent
this is to just manually add the path url `typo3/install.php` in the
browser to directly reach the installer, which will take care of the
trusted hosts pattern setting in one of its installer steps.

### Error displayed on an existing instance

You see this error, because the submitted HTTP host-header does not
match the `trustedHosts` configuration. You may want to adjust the trusted
host pattern, which is security mechanism to validate the HTTP
host-header and prevent host spoofing.

Please read the [security advisory
»TYPO3-CORE-SA-2014-001«](https://typo3.org/teams/security/security-bulletins/typo3-core/typo3-core-sa-2014-001/)
to understand the need for this configuration option.

The trusted host pattern may be set with the Install Tool (**Backend** \>
**Install Tool** \> **All configuration** \> **Toggle all** and find
**trustedHostsPattern**) or by editing `/typo3conf/LocalConfiguration.php`.

```
$GLOBALS['TYPO3_CONF_VARS']['SYS']['trustedHostsPattern']

```

This is a regular expression pattern that matches all allowed hostnames
(including their ports) of this TYPO3 installation, or the string
"SERVER_NAME" (default). The default value `SERVER_NAME` checks if the
HTTP Host header equals the `SERVER_NAME` and `SERVER_PORT`. This is secure
in correctly configured hosting environments and does not need further
configuration.

Under certain circumstances, it might be required to change the default
configuration. A typical case is a hosting setup with a Load Balancer,
CDN or a HA proxy.

#### Typical configuration examples

The following matches all hosts that end with **.domain.com** with all
corresponding subdomains:

```
.*\.domain\.com

```

A common setup could include the leading **www.** (optional):

```
(www\.)?domain\.com

```

The following matches all hosts with subdomains under **.domain.com**
and **.otherdomain.com**:

```
(.*\.domain|.*\.otherdomain)\.com

```

Be aware that HTTP Host header may also contain **a port**. If your
installation runs on a specific port, you need to explicitly allow this
in your pattern. To allows only www.domain.com:88, not www.domain.com,
you could configure:

```
www\.domain\.com:88

```

To disable this check completely (not recommended because it is
insecure) you can use ".\*" as pattern:

```
.*

```

## Extension 'hosts_pattern'

Take a look at the extension 'hosts_pattern' which generates the
patterns for you

-   [https://extensions.typo3.org/extension/hosts_pattern/](https://extensions.typo3.org/extension/hosts_pattern/)