Worked for me as well.
I had a similar error after successful installation with cmd line.
My error was:
1 exception(s): Exception #0 (Exception): Warning: Undefined variable $Path in C:\xampp\htdocs\mage2rock\vendor\magento\framework\View\Element\Template\File\Validator.php on line 140 Exception #0 (Exception): Warning: Undefined variable $Path in C:\xampp\htdocs\mage2rock\vendor\magento\framework\View\Element\Template\File\Validator.php on line 140 <pre>#1 Magento\Framework\View\Element\Template\File\Validator->isPathInDirectories() called at [vendor\magento\framework\View\Element\Template\File\Validator.php:117] #2 Magento\Framework\View\Element\Template\File\Validator->isValid() called at [vendor\magento\framework\View\Element\Template.php:260] #3 Magento\Framework\View\Element\Template->fetchView() called at [vendor\magento\framework\View\Element\Template.php:293] #4 Magento\Framework\View\Element\Template->_toHtml() called at [vendor\magento\framework\View\Element\AbstractBlock.php:1095] #5 Magento\Framework\View\Element\AbstractBlock->Magento\Framework\View\Element\{closure}() called at [vendor\magento\framework\View\Element\AbstractBlock.php:1099] #6 Magento\Framework\View\Element\AbstractBlock->_loadCache() called at [vendor\magento\framework\View\Element\AbstractBlock.php:660] #7 Magento\Framework\View\Element\AbstractBlock->toHtml() called at [vendor\magento\framework\View\Result\Page.php:251] #8 Magento\Framework\View\Result\Page->render() called at [vendor\magento\framework\View\Result\Layout.php:171] #9 Magento\Framework\View\Result\Layout->renderResult() called at [vendor\magento\framework\Interception\Interceptor.php:58] #10 Magento\Framework\View\Result\Page\Interceptor->___callParent() called at [vendor\magento\framework\Interception\Interceptor.php:138] #11 Magento\Framework\View\Result\Page\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor\magento\framework\Interception\Interceptor.php:153] #12 Magento\Framework\View\Result\Page\Interceptor->___callPlugins() called at [generated\code\Magento\Framework\View\Result\Page\Interceptor.php:95] #13 Magento\Framework\View\Result\Page\Interceptor->renderResult() called at [vendor\magento\framework\App\Http.php:120] #14 Magento\Framework\App\Http->launch() called at [generated\code\Magento\Framework\App\Http\Interceptor.php:23] #15 Magento\Framework\App\Http\Interceptor->launch() called at [vendor\magento\framework\App\Bootstrap.php:264] #16 Magento\Framework\App\Bootstrap->run() called at [pub\index.php:30] </pre>