Exchange 2013 Security Update for Exchange CU11 Error: RPC Over HTTP Autoconfig (Event ID 2002)

We recently installed Security update for Microsoft Exchange Server CU11 (KB3124557) on our multi-role Exchange 2013 servers, and after the rollout, one server started throwing MSExchange RPC Over HTTP Autoconfig (Event ID 2002) errors, and it happened every 15 minutes. To go along with the errors, some users reported that Outlook started reporting "Microsoft Exchange administrator has made a change that requires you quit and restart Outlook".

The problem (it seems) that the update itself is buggy; I've seen other reports on forums that it broke their Exchange 2013/2016 machines.

The full error is:

Log Name:      Application
Source:        MSExchange RPC Over HTTP Autoconfig
Date:          3/2/2016 4:49:02 PM
Event ID:      2002
Task Category: General
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      MBX-03.domain.com
Description:
An unexpected failure has occurred. The problem will require administrator intervention. The service will retry in 00:15:00. Diagnostic information:
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite, Boolean checkHost)
   at Microsoft.Exchange.Servicelets.RPCHTTP.RPCHTTPServicelet.CopyCustomRpcProxyFiles()
   at Microsoft.Exchange.Servicelets.RPCHTTP.RPCHTTPServicelet.ConfigureRpcForMailboxServer(Boolean isAlsoFrontEnd)
   at Microsoft.Exchange.Servicelets.RPCHTTP.RPCHTTPServicelet.Work()
The process cannot access the file 'C:\Windows\System32\RpcProxy\RpcProxyShim.dll' because it is being used by another process.

**Note** The server name has been changed to protect the innocent.

I was hesitant to remove the update, because I've seen in the past that doing so sometimes has terrible effects on Exchange, but I had no other choice.

I uninstalled the KB3124557 update, and the installer called for the original CU11 install files, so make sure you have those handy.

After uninstalling, it disabled and stopped all Exchange services - even on other Exchange servers, so you'll definitely want to do this in a maintenance window.
I thought no big deal it will re-enable them when we re-install the update. Re-installing the update did not fix the services.

So the only course of action was to entirely remove the update, and manually switch the services to automatic and start them.

**Note** We uninstalled the update on all of our Exchange servers, so they are all on matching patch levels.

These are the Exchange services you'll need to enable and start:

Windows Management Instrumentation
World Wide Web Publishing Service
Tracing Service for Search in Exchange
Remote Registry
Performance Logs & Alerts
IIS Admin Service
Application Identity
Microsoft Filtering Management Service
Microsoft Exchange Unified Messaging
Microsoft Exchange Transport Log Search
Microsoft Exchange Transport
Microsoft Exchange Throttling
Microsoft Exchange Service Host
Microsoft Exchange Search Host Controller
Microsoft Exchange RPC Client Access
Microsoft Exchange Replication
Microsoft Exchange POP3
Microsoft Exchange Mailbox Transport Submission
Microsoft Exchange Mailbox Replication
Microsoft Exchange Mailbox Assistants
Microsoft Exchange Information Store
Microsoft Exchange IMAP4
Microsoft Exchange Health Manager
Microsoft Exchange Frontend Transport
Microsoft Exchange Search
Microsoft Exchange EdgeSync
Microsoft Exchange Diagnostics
Microsoft Exchange Mailbox Transport Delivery
Microsoft Exchange DAG Management
Microsoft Exchange Anti-spam Update
Microsoft Exchange Active Directory Topology

We restarted the Exchange servers themselves for good measure, and everything is back to normal. I'm just gonna wait until Exchange 2013 CU12 drops and install that...to hell with this update :)