It is possible to manually upgrade each agent, but that is just wasting time on something really boring, so let us do PowerShell instead

#Get the Admin Account
$AdminAccount = Get-SCRunAsAccount -Name ‘SCVMM Admin’

#Update the Agent
foreach($item in (Get-SCVMMManagedComputer)){
    Update-SCVMMManagedComputer -VMMManagedComputer $item -Credential $AdminAccount -RunAsynchronously
}

/mike