I had an issue with one of my DC's which was my CA. I only have one
Enterprise CA on a single forest single domain AD. Windows 2003 functional
level.

I backed up my CA, Stoped my CA service, backed up the registry
(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\CertSvc\Configuration\"mydomain Root CA")

I then uninstalled CA service, DCpromo demoted the server. Rebooted.
DCpromo - verified that all went well. dcdiag - all good.

I then reinstalled CA, custom. used my backedup certificate. Stopped
service, restored registry key, restored CA from backup and allowed it to
"start service". Here is were it all fell apart. I am getting:
"Microsoft Certificate services - Bad Key, 0x80090003 (-2146893821)"

Event log: Application

Event Type: Error
Event Source: CertSvc
Event Category: None
Event ID: 100
Date: 9/5/2008
Time: 12:05:07 PM
User: N/A
Computer: mydc2
Description:
Certificate Services did not start: Could not load or verify the current CA
certificate. MyDomain Root CA Bad Key. 0x80090003 (-2146893821).

For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.


I look forward to any advice you can provide.

--
Fredrick A. Zilz
Director IT
InterHealth N.I.

RE: CA Restore by Onion

Onion
Fri Sep 05 14:27:19 PDT 2008

It sounds like you did the backup/restore correctly. You can also turn on
debug logging (logs to %systemroot%\cert#.log) to help determine the root
cause of the issue:

certutil -setreg ca\debug 0xffffffe3