The Exchange 2010 SP2 RU5 update was removed from the download centre last month.  The V2 of this update is now available and resolves issues with the Get-DatabaseAvailabilityGroup cmdlets.  With the v1 of the update installed this error may have been observed:

WARNING: An unexpected error has occurred and a Watson dump is being generated: Could not load type 'Microsoft.Exchange.Rpc.ActiveManager.AmDeferredRecoveryEntry' from assembly 'Microsoft.Exchange.Rpc, Version=14.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

To remediate the issue, uninstall the RU5v1 update.

You can review the fix list for V1 of the update in a previous post.  If you contrast the previous fix list and the new one, there is an addition at the bottom:

Now, before we rush off to download and install this there are a couple of items to mention!

• Test the update in your lab before installing in production.  If in doubt test…
• If the Exchange server does not have Internet connectivity then this introduces significant delay in building the Native images for the .Net assemblies as the server is unable to get to http://crl.microsoft.com.  To resolve this issue, follow these steps:
  1. On the Tools menu in Windows Internet Explorer, click Internet Options, and then click the Advanced tab.
  2. In the Security section, click to clear the Check for publisher's certificate revocation check box, and then click OK.
  We recommend that you clear this security option in Internet Explorer only if the computer is in a tightly controlled environment. When setup is complete, click to select the Check for publisher’s certificate revocation check box again.
• Update Internet facing CAS servers first
• Test (yes technically this is in here for a second time but it is important!)

All this and extra detail can be found in the accompanying KB article 2785908.

Cheers,

Rhoderick