Just after clicking "Begin installation", after having verified that all settings were ok, I got this message with no way to continue or go back:
I did a search and found something looking somewhat like it. That user had solved his problem by reinstalling the package and running the install again. Also, for some weird reason my other mySQL database (one I used for the forum I'm currently upgrading to XenForo) seems to have become corrupted because of this. They don't have the same name of course.
Server Error Mysqli statement execute error : Error writing file '/mysql-tmp/MLxysR5n' (Errcode: 28) Zend_Db_Statement_Mysqli->_execute() in Zend/Db/Statement.php at line 297 Zend_Db_Statement->execute() in Zend/Db/Adapter/Abstract.php at line 479 Zend_Db_Adapter_Abstract->query() in XenForo/Model/AdminTemplate.php at line 723 XenForo_Model_AdminTemplate->compileParsedAdminTemplate() in XenForo/Model/AdminTemplate.php at line 602 XenForo_Model_AdminTemplate->compileAllParsedAdminTemplates() in XenForo/Deferred/AdminTemplate.php at line 16 XenForo_Deferred_AdminTemplate->execute() in XenForo/Deferred/Atomic.php at line 61 XenForo_Deferred_Atomic->execute() in XenForo/Model/Deferred.php at line 208 XenForo_Model_Deferred->runDeferred() in XenForo/Model/Deferred.php at line 331 XenForo_Model_Deferred->_runInternal() in XenForo/Model/Deferred.php at line 265 XenForo_Model_Deferred->runByUniqueKey() in XenForo/Install/Controller/Abstract.php at line 34 XenForo_Install_Controller_Abstract->_manualDeferredRunner() in XenForo/Install/Controller/Install.php at line 221 XenForo_Install_Controller_Install->actionRunDeferred() in XenForo/FrontController.php at line 337 XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134 XenForo_FrontController->run() in /hermes/bosoraweb185/b2140/dom.teslataxime/xenForo/install/index.php at line 18