**TL;DR:**

The Backend Layouts of the site package tutorial (Default/Standard and Two Columns) do not show up for new pages in Appearance -> Backend Layout. The error message in this thread (1.html) is an artefact of prior Backend Layouts which came from the original old site setup.

**Solution:**

To make the Backend Layouts of the site package tutorial show up there, I had to edit the root page of the site: Resources -> Include static Page TSconfig (from extensions) and add site-package from the Available Items list.
This can also be achieved without "Resources -> Include static Page TSconfig (from extensions)" but via file `ext_localconf.php` in the root of the site package extension (`gpcf_theme`):

```
<?php
defined('TYPO3_MODE') || die();

$boot = function (string $_EXTKEY): void {
        \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPageTSConfig('
                <INCLUDE_TYPOSCRIPT: source="FILE:EXT:'.$_EXTKEY.'/Configuration/TsConfig/Page/Page.tsconfig">
        ');
};
$boot('gpcf_theme');
unset($boot);

```

**Original Question:**

I'm still trying to bring an existing (older) web page into Typo3 11 following the TYPO3 Sitepackage Tutorial.

Currently I get an

```
"Oops, an error occurred! Code: 202111161210589c32f8c0"

```

and can't get rid of it whatever I do.

The corresponding entry in the log files is (line breaks added by me):

```
../../var/log/typo3_61306f633c.log:Tue, 16 Nov 2021 12:10:58 +0000 [ALERT] request="30cc4e082c853" 
component="TYPO3.CMS.Frontend.ContentObject.Exception.ProductionExceptionHandler": 
Oops, an error occurred! Code: 202111161210589c32f8c0- InvalidTemplateResourceException:
Tried resolving a template file for controller action "Standard->1" in format ".html",
but none of the paths contained the expected template file (Standard/1.html).
The following paths were checked: 
/var/www/html/typo3_11/public/typo3conf/ext/gpcf_theme/Resources/Private/Templates/Page/, 
in file /var/www/html/typo3_11/vendor/typo3fluid/fluid/src/View/TemplatePaths.php

```

I can't find the reason of this error, because I have no idea, where the needed template Standard/1.html is requested from.

Is this some kind of hard coded default if nothing else is found?
If this is the case, the real problem is, that my customizations to the Sitepackage Tutorial source code seems to be wrong, but it never produced any different error despite the above one, which isn't really helpful. Ok, this is speculation, because I don't know.

As you can see, the site package was renamed to gpcf\_theme, it's available in the backend and applied as root template to the site. No other template is active (AFAIK). A simple newly created test page creates above error.

If I uncomment in Configuration/TypoScript/Setup/Page.typoscript the lines so that:

```
page = PAGE
page {
  typeNum = 0
  10 = TEXT
  10.value = Hello World!
}

```

same error, no hello world.

Any idea how to locate the reason for my misery?