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During a reinstall of Exchange 2007, I encountered this error:

This problem may have occurred as a consequence of using the Windows Installer Cleanup Utility.

The following details the steps I took to resolve this problem.


Error Message


Error code is 1603. Last error reported by the MSI package is ‘Could not open key: UNKNOWN\Components\… Verify that you have sufficient access to that key, or contact your support personnel.





1. Start regedit

2.Navigate to the key that is described in your error message.

It should be located under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Components

It should be sub-keys under the key that you have navigated to that will have a problem. You may find that there is an error message as you click each of those sub-keys.

3. Return to the key that is described in your error message.

4. Right-click on it and select Permissions

5. Click on the Advanced button

6. In the resultant window, tick ‘Replace all existing inheritable permissions…’

7. Click OK.

If you do not get an error message at this stage, then you have likely resolved the problem.

8. Click on through to return back to the regedit main window

9. Close regedit


If the registry fix did not work and you still found that clicking the sub-keys off of the main key mentioned in the error message, resulted in another error, then it is time to try Safe Mode.

I found that when I entered Safe Mode and started working on the server directly, I found that I still could not modify those sub-keys whilst logged in as Administrator.

Fearing that there was now something wrong with my Administrator login, I looked to use an alternative admin login. But before I did that, I tried adding the Administrator account to the Server Operators group.

And on logoff/logon I was able to finally modify the permissions on those sub keys.

Reboot to get out of Safe Mode.

You should now be able to run the Exchange 2007 setup.

I hope that this has helped you in some way.

Did it work for you? If it didn’t, there are a couple of other things you could try:

  1. Reset the security database
  2. Reset permissions with SubInACL utility

I haven’t detailed these methods, mainly to keep this blog short. But if you ‘d like me to detail these, let me know!



Reset the security database

Download the SubInACL utility


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