Recover a TYPO3 website which got broken after installing an extension

Sometimes, you have a perfectly working TYPO3 website. Then you install a new extension and then BOOM !!!! everything breaks. Sometimes, you can’t even access the backend anymore. So how do you recover your website?

You have to deactivate the extension you just installed which caused this error. Since you cannot access the backend, you have to do this manually.

The steps below were tested on TYPO3 8 and 9,

• Open the typo3conf/PackageStates.php file.
• Search for the extension key of the extension to be deactivated in this file.
• Delete the array item whose key is the same as the extension key of the extension to be deactivated.
• For example if you wanted to deactivate an extension with extension key vhs, the code below will be removed from the typo3conf/PackageStates.php file.

'vhs' => [
    'packagePath' => 'typo3conf/ext/vhs/',
],

• Delete the typo3temp folder. Don’t be scared, this folder will be regenerated by TYPO3.
• Reload your website and everything should now run smoothly.

The extension has been deactivated and your website recovered.