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Fixing "error code 8202" When Installing Exchange 2007

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This article is intended to extend and better explain the solutions presented here:

This solution, and the solution of the above articles, is intended to fix the “ldifde.exe error code 8202” issue that may arise when attempting to install Exchange 2007 on Windows Server 2008 R2.

1) For my screenshots, I am simulating this error.  I have manually added the “DUP” and the GUIDs to the values so that you can see what they look like. Also, in an attempt to as closely emulate what you will see, I have not edited the screenshots to remove my server or domain names. Please do not use any of this information in a manner that would make my job more difficult. Thank you.

2) This issue would seem to arise from attempting to install Exchange 2007 a second time after an initial install has failed.
Follow these steps:


From a server on the domain in which Exchange is being installed, run the ADSI Edit utility:


Right click ADSI Edit and select Connect To. Select the well known naming context Schema


Navigate to “CN=ms-Exch-Resource-Schema” and double click it.


Locate the mayContain field.  Open it and look for any items that have “DUP” and a GUID attached to it (see image for an example).


This is where the steps from the Microsoft articles get confusing.  If you try to modify the “DUP” value you will get the following error:
Operation failed. Error code: 0x57
The parameter is incorrect.

00000057: ldapErr: DSID-0C090B7C, comment: Error in attribute
conversion operation, data 0, v1db0

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Instead, you need to navigate to another CN key inside the schema. In the example, the value that has the “DUP” is the “msExchResourcePropertyScheme”.  You would need to navigate to
From there, locate the attribute “lDAPDisplayName”.  Change the value of the attribute to remove the “DUP” and the GUID.image008dv.jpg


Press “OK” and wait for replication (or force replication).  Once everything has replicated, attempt your Exchange 2007 installation again.  The problem should be resolved and your AD schema should update correctly.

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