Microsoft Exchange Server Auth Certificate is a self-signed certificate that allows connection with other servers like Lync, SharePoint, etc. These certificates are created at the time of the installation of Exchange Server. Exchange administrators can get the certificates information through the Exchange Admin Center at servers > certificates. It needs to be renewed as it has an expiration date.

Issue

Many user queries say that they have a successful deployment of their Exchange Server version, but when they try to access OWA, an error pop up like this.
’Federation or Auth certificate not found: “Certificates-thumbprint.” Unable to find the certificate in the local or neighboring sites. Confirm that the certificate is available in your topology and if necessary, reset the certificate on the Federation Trust to a valid certificate using Set-FederationTrust or Set-AuthConfig. The certificate may take time to propagate to the local or neighboring sites.’
The error itself describes that the certificate is missing or cannot be configured. This disturbs the server to server authentication and communication and even blocks accessing those servers.

Fix Microsoft Exchange Server Auth Certificate Missing Error

This issue of missing Exchange Server Auth Certificate can be resolved by creating a new certificate using cmdlets in the Exchange Management Shell. The process of running cmdlets requires technical knowledge as well as great care to avoid any further error. Also, the user must have Exchange administrator rights to perform this procedure. If you have all this, start the process as instructed below:

1. Open the Exchange Management Shell on your Exchange 2016/2013 server.
2. Run this command to create a new Exchange Auth certificate.
   New-ExchangeCertificate -KeySize 2048 -PrivateKeyExportable $true -SubjectName “CN= Microsoft Exchange Server Auth Certificate” -DomainName “*.enterdomainname.com” -FriendlyName “Microsoft Exchange Server Auth Certificate” -Services SMTP

   For example:
   

3. Once, the above command is run, it will ask you if you want to overwrite the existing default SMTP certificate. Type N and press Enter.
   
   A certificate thumbprint will get created here. You need to note down this alpha-numeric certificate thumbprint somewhere as you would require it in the next cmdlet.
4. Run this next command to save the present date to the object.
   $date = Get-Date

   

5. Now, to set the authentication configuration for Exchange, execute the following cmdlet.
   Set-AuthConfig -NewCertificateThumbprint <certificate_thumbprint> –NewCertificateEffectiveDate $date

   
   When you execute the above command, it asks to confirm regarding the effective date of the certificate. Confirm it by typing Y and pressing Enter.

6. Next command should be run to publish the new created Exchange Auth certificate.
   Set-AuthConfig –PublishCertificate

   
   Note: If you have any previously installed Exchange certificate, you need to clear it with the following command.

   Set-AuthConfig -ClearPreviousCertificate
7. Finally, run this cmdlet to reset the ISS service for all CAS and mailbox servers.
   IISRESET

Thus, you can fix the error ‘the Exchange Auth Certificate is missing.’

Apart from this error, there are many other Exchange errors and issues administrators face in the Exchange environment. Though we have some free methods to convert EDB to PST in case of corruption issue also, using them would be a tedious and risky task. So, we undoubtedly recommend the Exchange users stuck in these situations to go for the best Exchange Recovery solution. Kernel for Exchange Server is the best Exchange Server recovery tool which deals with all problems related to Exchange database and then recover inaccessible Exchange mailboxes to various destinations like PST, Live Exchange, Office 365, etc. Try its efficient features with its demo version which is available free for download on the site.

Summing Up

We have discussed the manual solution for fixing Exchange Auth Certificate missing error. And for Exchange administrators who are facing other types of issues like EDB file corruption, a complete third-party tool to deal with all Exchange errors is also recommended at the end.