MsExchange Blog Spot Telnet25

February 9, 2010

Recover Failed Exchange Server with /M:RecoverServer Switch

Filed under: General — telnet25 @ 5:33 am


One of your Exchange CAS box crashed, and you have no way of getting it back. As many of you know bringing another Exchange server with same name and IP address wont simply work because the information in regards to failed exchange server is still does exist in Active directory and Exchange utilize Domain, Configuration and Schema partitions in the .DIT database.

So we will use fallowing switch to perform installation, if this is a mailbox server please read the article Henrik wrote

You may ask yourself why are we using recovery switch, again we want setup to go to AD and read the information about failed server and make the new server we are bringing *** We use same IP and same server name***

Steps taken:

  • Install fresh Server ( in this case Windows 2008 Sp1)
  • Give same IP and Same computer name as previous failed Exchange server, Join domain and make sure your account is added into Local administrator and you have proper Exchange administrator rights.
  • Reset computer account in AD
  • Make sure Server is identical as the failed one, keep same drive letters etc
  • Copy Exchange installation binaries onto this server
  • Drill to that directory and use fallowing switch
> /M:RecoverServer

**** if you are receiving fallowing errors, fallow the additional steps before you move on ****

“You must perform disaster recovery using the same version of Exchange as the last installed version. The current installed version is ‘’ the last installed version was ‘’

This translated into , simply The failed Exchange Server version number is SP2, you are using Exchange CD with SP1 and trying to run recovery switch.

As you can see setup is going to AD and reading attribute called “SerialNumber" from failed server object so what we will have to do little trick in AD and modify this attribute.


Open ADSIedit or ADExplorer   to

  • Configuration
  • Services
  • Administrative Groups
  • CN=ServerName

Find the attribute called SerialNumber and modify it.


if you are receiving this “

The current installed version is the last installed version was”

  • Current Version 8.2 (Build 30176.2)  (SP2)
  • installed version is ( build 30240.6) (SP1)




Check out the build numbers.

Change the version number to , allow the setup to run, without complaining


Oz Casey , Dedeal

MCSE 2003, M+, S+, MCDST
Security+, Project +, Server +

Http:// (Blog

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1 Comment »

  1. WOW thanks for this. Really helpful. I wish we could have come across this post last month when one of our servers bogged down!

    Comment by Exchange email hosting — April 21, 2010 @ 7:53 am | Reply

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