title: Class '\t3lib_cache_backend_FileBackend' not found
body: <p>After updating TYPO3 from 4.5 to 7.6 and a PHP update from 5.3 to 5.5 I get this error in the install tool:</p>
  
  <blockquote>
    <p><strong>Detected Fatal Error</strong></p>
    
    <p>Class '\t3lib_cache_backend_FileBackend' not found in
    /var/www/htdocs/typo3src/typo3_src-7.6.9/typo3/sysext/core/Classes/Cache/CacheFactory.php
    on line 76</p>
  </blockquote>
  
  <p>PHP-Version is 5.5.36. 
  A new download of the TYPO3 src did not solve it. </p>