Free/Busy Federation Troubleshooting

I have had the pleasure of being the administrator of the very first organization to implement the new Exchange 2010 Free/Busy Federation (from now on I will call it F/B Fed) infrastructure last year during the Exchange 2010 TAP (Technical Adaption Program).  In doing so, I have been given the opportunity to work directly with a couple of the Microsoft Exchange Product Group members (thank you Ladislau and Matthias!!!) that guided me through the initial implementation and troubleshooting of Free/Busy Federation when it occasionally went awry.  I could probably write a small whitepaper on what I have learned, however for the purposes of this blog post, I wanted to delve into the latest issue I had. 

Recently, the public certificate we had been using for OWA, etc… and therefore for F/B Fed was going to expire and the cert vendor had made some changes to the UC certs they offered so we had to make a cert change, not just a renewal.  After we installed the new certificate and began using it for all the other web services (OWA, OA, EAS, etc…), we turned to F/B Fed and ran two commands with the intent of rolling to the new certificate.

Set-FederationTrust -Identity MyFederationTrust -Thumbprint <your new cert thumbprint here>

Set-FederationTrust "MyFederationTrust" –PublishFederationCertificate

The problem is, it didn’t work.  The new certificate didn’t get rolled to as it should have.  Instead, I received the error shown below.

An error occurred accessing Windows Live. Detailed information: "The request failed with HTTP status 403: Forbidden.". + CategoryInfo: ResourceUnavailable: (:) [Set-FederationTrust], LiveDomainServicesAccessException + FullyQualifiedErrorId: 7CDAC73F,Microsoft.Exchange.Management.SystemConfigurationTasks.SetLiveFederationTrust

Next, I validated that the new certificate was in fact valid and that the certificate was enabled for Server Authentication.

So Far, everything looked ok, but we still couldn’t roll the cert properly and federation had stopped working as well.  ARGH..

After a bit more trial and error, it had seemed like the Set-FederationTrust command shown earlier had finally worked, at least it didn’t give me an error when I ran it, however, F/B Fed still wasn’t working and when I ran Test-FederationTrust –Verbose, I received the following error in response.

RunspaceId : xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx Id         : OrganizationPreviousCertificate Type       : Error Message    : Certificate referenced by property OrgPrevPrivCertificate in the FederationTrust object is expired.

With the help of Matthias, I ran the following script in order to attempt to push the old certificate completely out of the Federation system.

$a = Get-FederationTrust

Set-FederationTrust -Identity $a.Identity -Thumbprint $a.OrgPrivCertificate

Set-FederationTrust -Identity $a.Identity –PublishFederationCertificate

Unfortunately, when I ran the second command, I received a new error.

Federation certificate with thumbprint "C54359E291F10213…" must have a unique Subject Key Identifier.  The Subject Key Identifier "1A29F0C8C62971EA524BE4…" is already used by the certificate with thumbprint "C54359E291F10213…". + CategoryInfo: InvalidArgument: (:) [Set-FederationTrust], ProvisionerConfigException + FullyQualifiedErrorId: 4CFC5CA6,Microsoft.Exchange.Management.SystemConfigurationTasks.SetLiveFederationTrust

So, it seemed at the time that the issue was more of a security one due to the beta we are running for Service Pack 1, so we tried a different approach.

$a = get-federationtrust

$b = "LDAP://" + $a.DistinguishedName

$c = [ADSI]$b

If ($c.msExchFedOrgPrevPrivCertificate -ne $null) { $c.PutEx(1, "msExchFedOrgPrevPrivCertificate", 0) }

If ($c.msExchFedOrgPrevCertificate -ne $null) { $c.PutEx(1, "msExchFedOrgPrevCertificate", 0) }

$c.SetInfo()

I ran that script (without error) and waited for AD to replicate.  Afterwards, I ran Test-FederationTrust –Verbose again, this time with a slightly different error, yet still related to the “msExchFedOrgPrevPrivCertificate” attribute.

RunspaceId : xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx Id         : OrganizationPreviousCertificate Type       : Error Message    : Unable to find certificate referenced by property OrgPrevPrivCertificate in the FederationTrust object.

Hmmm…  that is interesting, now I don’t have a value in that attribute at all!  So I checked that by running Get-FederationTrust | fl and sure enough, this attribute was empty from Exchange’s point of view.  However, not fully convinced, Ladislau recommended I run the script below just to ensure it really was missing from AD.

$a = get-federationtrust

$b = "LDAP://" + $a.DistinguishedName

$c = [ADSI]$b

$c | fl * -force

And of course, it was actually missing from AD as well….

Come to find out, I had hit a new unknown bug on cert rolling and had to run this final script to set the msExchFedOrgPrevPrivCertificate attribute and get F/B Fed working again.

$a = get-federationtrust

$b = "LDAP://" + $a.DistinguishedName

$c = [ADSI]$b

$c.msExchFedOrgPrevPrivCertificate = $c.msExchFedOrgPrivCertificate

$c.SetInfo()

Now, when I run Test-FederationTrust –Verbose I get a “Success” on all tests!  And our users are happy because Free/Busy Federation is once again working as advertised.  I hope these little insights are helpful to others when they use their favorite search engine to find answers to their own Federation issues. 

Until next time…