Unable to save site as template + unexpected error.

when we document library [void][System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint")
[void][System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Administration")
$docSize = 5000000000
$webservice = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$webservice.MaxTemplateDocumentSize = $docSize
$webservice.Update()