2. Change the filename of local.xml.sample to local.xml
3. Reload the page where it shows error message, you will see a full list of error message – The purpose of rename local.xml is to allow the full error message to be shown.
4. Now, locate magento_directory/lib/Zend/Cache/Backend/File.php and look for:
protected $_options = array(
'cache_dir' => 'null',
Replace it with:
protected $_options = array(
'cache_dir' => 'tmp/',
And save the file.
5. Now, go to Magento root directory and create a new directory with the name “tmp”.
6. Refresh the error page and see if the issue solved.