Hi all, I'm just too tired to look into this error this evening. For the dozen or so installations I've performed I've not seen this error yet, so I'll post it up here and see if anyone else has before I get back into it tomorrow morning. Without further ado, here is the error text (below the signature, since it's rather lengthy). Cheers, Lain Summary: 11 item(s). 9 succeeded, 1 failed. Elapsed time: 00:07:36 [...snip...] Mailbox Role Failed Error: The following error was generated when "$error.Clear(); $name = [Microsoft.Exchange.Management.RecipientTasks.EnableMailbox]::DiscoveryMailboxUniqueName; $dispname = [Microsoft.Exchange.Management.RecipientTasks.EnableMailbox]::DiscoveryMailboxDisplayName; $dismbx = get-mailbox -Filter {name -eq $name} -IgnoreDefaultScope -resultSize 1; if( $dismbx -ne $null) { $srvname = $dismbx.ServerName; if( $dismbx.Database -ne $null -and $RoleFqdnOrName -like "$srvname.*" ) { Write-ExchangeSetupLog -info "Setup DiscoverySearchMailbox Permission."; $mountedMdb = get-mailboxdatabase $dismbx.Database -status | where { $_.Mounted -eq $true }; if( $mountedMdb -eq $null ) { Write-ExchangeSetupLog -info "Mounting database before stamp DiscoverySearchMailbox Permission..."; mount-database $dismbx.Database; } $mountedMdb = get-mailboxdatabase $dismbx.Database -status | where { $_.Mounted -eq $true }; if( $mountedMdb -ne $null ) { $dmRoleGroupName = "Discovery Management"; $dmRoleGroup = Get-RoleGroup -Identity $dmRoleGroupName -DomainController $RoleDomainController -ErrorAction:SilentlyContinue; if( $dmRoleGroup -ne $null ) { Add-MailboxPermission $dismbx -User $dmRoleGroup.Identity -AccessRights FullAccess -DomainController $RoleDomainController -WarningAction SilentlyContinue; } } } }" was run: "Couldn't mount the database that you specified. Specified database: Mailbox Database 1191853761; Error code: An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233) [Database: Mailbox Database 1191853761, Server: server01.domain.edu.au].". Couldn't mount the database that you specified. Specified database: Mailbox Database 1191853761; Error code: An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233) [Database: Mailbox Database 1191853761, Server: server01.domain.edu.au]. An Active Manager operation failed. Error: The database action failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233) [Database: Mailbox Database 1191853761, Server: server01.domain.edu.au] An Active Manager operation failed. Error: Operation failed with message: MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233) [Server: server01.domain.edu.au] MapiExceptionNotFound: Unable to mount database. (hr=0x8004010f, ec=-2147221233) Elapsed Time: 00:02:22 Finalizing Setup Cancelled

This solution ended up being the same as I found from testing in the migration domain: re-enable inheritance so that permissions can propagate from the domain object onto the delegated OU structure below. That enabled the mailbox role installation process to succeed and I will be able to once again stop inheritance, leaving the Exchange permissions in place where appropriate. Cheers, Lain