Error when trying to change the password for a Managed Account in SharePoint 2010:

Error deploying administration application pool credentials.
Another deployment may be active. An object of the type
Microsoft.SharePoint.Administration.SPAdminAppPoolCredentialDeploymentJobDefinition named
“job-admin-apppool-change” already exists under the parent Microsoft.SharePoint.Administration.SPTimerService named “SPTimerV4”. Rename your object or delete the existing object.

In my case, I needed to change the account that the SharePoint 2010 Timer service was running as. Every time I tried to update the password, the Timer would stop and the update would fail. Once I changed the Run As of the Timer, I was able to update the password.

Add-PSSnapin Microsoft.SharePoint.PowerShell -EA silentlycontinue

$m = Get-SPManagedAccount -Identity "domain\YourAccount"

Set-SPManagedAccount -Identity $m  -ExistingPassword (ConvertTo-SecureString "Your PASSWORD" -AsPlainText -force) –confirm