I get this error when I try to print an invoice:
Fatal error: Declaration of Zend_Pdf_FileParserDataSource_File::__construct() must be compatible with Zend_Pdf_FileParserDataSource::__construct() in /home/theanima/public_html/lib/Zend/Pdf/FileParserDataSource/File.php on line 41
I believe that I have upgraded to CE1.9 but it says it is still CE1.5.1 on the bottom of the window.
Fixed it by change in this function
abstract public function __construct();
abstract public function __construct($filePath);
For more details follow this link Magento PHP 5.4 PDF invoice Zend error