This is quite interesting. I had a server with XF 1.2.5 up and running with CentOS 6.5 + centmin mod yesterday. I used about a 1 month old SQL dump for the old forum. I wanted to practice the installation and move to a 1.3 RC so I reverted the VM to a previous version, installed the new vhost, setup the MariaDB database, unzipped and copied files, changed directory permissions. I then launched the installer and after testing and adding MySQL config in step 2 I got the following errors: Code: Server Error Server Error Mysqli statement execute error : Can't create/write to file '/tmp/#sql_e651_0.MAI' (Errcode: 13) 1. Zend_Db_Statement_Mysqli->_execute() in Zend/Db/Statement.php at line 297 2. Zend_Db_Statement->execute() in Zend/Db/Adapter/Abstract.php at line 479 3. Zend_Db_Adapter_Abstract->query() in XenForo/Model.php at line 219 4. XenForo_Model->fetchAllKeyed() in XenForo/Model/StyleProperty.php at line 79 5. XenForo_Model_StyleProperty->getStylePropertiesInStyles() in XenForo/Model/StyleProperty.php at line 606 6. XenForo_Model_StyleProperty->rebuildPropertyCacheInStyleAndChildren() in XenForo/Model/StyleProperty.php at line 2434 7. XenForo_Model_StyleProperty->importStylePropertiesFromArray() in XenForo/Model/StyleProperty.php at line 2305 8. XenForo_Model_StyleProperty->importStylePropertyXml() in XenForo/Model/StyleProperty.php at line 2238 9. XenForo_Model_StyleProperty->importStylePropertyDevelopmentXml() in XenForo/Deferred/ImportMasterData.php at line 26 10. XenForo_Deferred_ImportMasterData->execute() in XenForo/Deferred/Atomic.php at line 66 11. XenForo_Deferred_Atomic->execute() in XenForo/Model/Deferred.php at line 256 12. XenForo_Model_Deferred->runDeferred() in XenForo/Model/Deferred.php at line 390 13. XenForo_Model_Deferred->_runInternal() in XenForo/Model/Deferred.php at line 316 14. XenForo_Model_Deferred->runByUniqueKey() in XenForo/Install/Controller/Abstract.php at line 34 15. XenForo_Install_Controller_Abstract->_manualDeferredRunner() in XenForo/Install/Controller/Install.php at line 236 16. XenForo_Install_Controller_Install->actionRunDeferred() in XenForo/FrontController.php at line 347 17. XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134 18. XenForo_FrontController->run() in /home/nginx/domains/test.(name changed).com/public/install/index.php at line 18 The same error occurred on a 1.2.5 installation so I knew something was wrong. I restarted the mysql and nginx services to no avail. Curiously, the fix was simply rebooting the VM. Hopefully this helps someone else.