title: php_warning on installing ext
body: <p>I want to intstall the ext &quot;my_redirects&quot;. On my local machine it does what it should. But now, on the live site, i got this error:</p>
  <h1>1: PHP Warning: file_get_contents(/kunden/homepages/28/d574274134/htdocs/update7/typo3/sysext/core/Resources/Private/Sql/Cache/Backend/Typo3DatabaseBackendCache.sql): failed to open stream: No such file or directory in /homepages/28/d574274134/htdocs/update7/typo3_src-7.6.14/typo3/sysext/core/Classes/Cache/Backend/Typo3DatabaseBackend.php line 441</h1>
  <p>I got a hint to delete the typo3temp/autoload/ files. Then the installation works, but if i after that go into the install tool, i get this error again. Can someone give a hint?</p>