Simples:
Sources/Packages.php
Encontra:
unction PackageInstallTest()
{
global $boarddir, $txt, $context, $scripturl, $sourcedir, $modSettings;
checkSession('get');
Substitui por:
function PackageInstallTest()
{
global $boarddir, $txt, $context, $scripturl, $sourcedir, $modSettings;
checkSession('request');