Typo3: Installed t3foundation v.9 on typo3 11.5.3 and now my Page is broken

Question

I installed the t3foundation v.9 on my typo3 v.11.5.3 system. It said it was not supported but i continued installing via extension manager. After Installation nothing worked. And I get the following error:

[07-Aug-2023 15:47:37 UTC] PHP Fatal error:  Uncaught Error: Call to a member function resolvePackagePath() on null in /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php:135
Stack trace:
#0 /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Utility/GeneralUtility.php(2762): TYPO3\CMS\Core\Utility\ExtensionManagementUtility::resolvePackagePath()
#1 /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Controller/ErrorPageController.php(47): TYPO3\CMS\Core\Utility\GeneralUtility::getFileAbsFileName()
#2 /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Utility/GeneralUtility.php(3217): TYPO3\CMS\Core\Controller\ErrorPageController->__construct()
#3 /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Error/ProductionExceptionHandler.php(65): TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance()
#4 /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Error/AbstractExceptionHandler.php(71): TYPO3\CMS\Core\Error\ProductionExceptionHandler->echoExceptionWeb()
#5 [internal function]: TYPO3\CMS\Core\Error\AbstractExceptionHandler->handleException()
#6 {main}
  thrown in /home/niruzbip/websites/dev.nirual-solutions.ch/typo3_src-11.5.30/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php on line 135

Can anyone help, how do I reverse this?

I already tried to take the extension out for the PackageStates.php but that didn't work.

Answer 1

1. Remove the extension out for the PackageStates.php
2. In the install tools (Maintenance) flush TYPO3 and PHP Cache and Rebuild PHP Autoload Information
3. If the install tools are broken delete the folder 'typo3temp/var/cache/'
4. In the install tools (Environment) generate the deleted folders again