Tag Archives: Windows

Exchange

The Kerberos client received a KRB_AP_ERR_MODIFIED error

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After starting an Exchange 2019 test environment, I noticed that several Exchange services would not start correctly. This happened on multiple Exchange 2019 servers. Sometimes, a reboot resolved it; sometimes, it went from all services running to several services not willing to start.

This particular test environment had four Exchange 2019 servers and three Windows 2022/2025 Domain Controllers in one Active Directory site.

On one Domain Controller I found several EventID 4 (Security-Kerberos) in the System Eventlog:

The Kerberos client received a KRB_AP_ERR_MODIFIED error from the server dc01$. The target name used was P365\DC01$. This indicates that the target server failed to decrypt the ticket provided by the client. This can occur when the target server principal name (SPN) is registered on an account other than the account the target service is using. Ensure that the target SPN is only registered on the account used by the server. This error can also happen if the target service account password is different than what is configured on the Kerberos Key Distribution Center for that target service. Ensure that the service on the server and the KDC are both configured to use the same password. If the server name is not fully qualified, and the target domain (P365LABS.NL) is different from the client domain (P365LABS.NL), check if there are identically named server accounts in these two domains, or use the fully-qualified name to identify the server.

Obviously, there’s a mismatch in system passwords. To resolve this, I used the following command:

netdom resetpwd /s:dc01 /ud:domain\administrator /pd:<domain admin password>

Reboot the Domain Controller, reboot the erratic Exchange server and everything is working fine again.

Windows

MMC crashes when managing SMTP service in Windows 2022

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Important note before I continue: The SMTP stack in Windows is a legacy of the old IIS6 service that was part of Windows 2003. As such, it is long out of support but it is still available in Windows 2022. You can use it, but it’s your own risk and there’s no support.

You can install the Windows SMTP Service on Windows 2022 using the following command:

Install-WindowsFeature -Name SMTP-Server,Telnet-Client -IncludeAllSubFeature -IncludeManagementTools -Restart

But when trying to manage the SMTP service, the MMC span-in crashes.

There’s an easy way to fix this by editing the MetaBase.xml file. Run the following commands:

Stop-Service SMTPsvc
Stop-Service IISAdmin

Under the IIsSmtpServer node, add a new line RelayIPList=”” as shown in the following screenshot:

Start the services again using the following PowerShell commands:

Start-Service IISAdmin
Start-Service SMTPsvc
Set-Service SMTPsvc -StartupType Automatic

You can use the last command to set the startup mode of the SMTP service to automatic (manual is the default setting).

You SMTP Service on Windows 2022 can now be managed using the MMC snap-in.

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Upgrade Windows Standard to Enterprise

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Note. When Exchange is installed on this particular server you can use this procedure only in a lab environment. To change an Exchange server is not a supported scenario!

When installing an Exchange 2010 environment in my lab I discovered that the Fail Over Clustering bits were not available on my planned DAG members. It turned out that I installed Windows 2008 R2 Standard Edition instead of Enterprise Edition. Even worse, Exchange Server 2010 SP2 was already installed as well.

On TechNet there’s an article that explains how to Upgrade Windows 2008 R2 without using the installation media (i.e. reinstall Windows 2008 R2 from scratch) using DISM, the Deployment Image Servicing and Management Tool.

Continue reading Upgrade Windows Standard to Enterprise →