I just ran the upgrader file and when I went to the module, I go this message:
Fatal error: Call to undefined method JInstaller::parseXMLInstallFile() in /hermes/waloraweb011/b2542/pow.paulleslie/htdocs/jupgrade/administrator/components/com_mobilejoomla/mobilejoomla.php on line 121

What Joomla version do you use?

I just applied the update from 1.1 to 1.2 and now I can't access Mobile Joomla on the backend. I get a 500 Internal Server Error when I try to access that area in the backend.

I am running Joomla 2.5.4. 

Thanks

As a temporary solution edit administrator/components/com_mobilejoomla/mobilejoomla.php by commenting 3 lines around that 121th line:

// if(version_compare(JVERSION, '2.5', '<'))
$xml = JApplicationHelper::parseXMLInstallFile($templateFile);
// else
// $xml = JInstaller::parseXMLInstallFile($templateFile);

PS. We tested MJ with J2.5.6 and J2.5.7, and forgot that there was significant update of Joomla Platform before 2.5.6.

That worked for me. I have access to the MobileJoomla backend now.

Please let me know when there is a permanent solution.

Fantastic - it worked for me as well. Thanks for your very prompt reply! I am using 2.5.4

As it's minor fix (affects J!2.5.0-2.5.4), we have updated MJ1.2 silently. You can reinstall MJ or wait for next release ("temporary solution" means that this code will be overwritten on next MJ update).