SSM agent service failed to start on windows-server 2019 (datacenter)

Question

I want to connect the instance with windows-server 2019 datacenter as OS. 
But the SSM agent service cannot be started either by Power Shell or windows service manage panel.

In Powershell, it prompt like below.

```
Start-Service : Failed to start service 'Amazon SSM Agent (AmazonSSMAgent)'.
At line:1 char:1
+ Start-Service AmazonSSMAgent
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OpenError: (System.ServiceProcess.ServiceController:ServiceController) [Start-Service],
   ServiceCommandException
    + FullyQualifiedErrorId : StartServiceFailed,Microsoft.PowerShell.Commands.StartServiceCommand
```

Meanwhile, I have created ssm-user and added it to Admin group. But it is not helpful towards issue.

I believe it is SSM configuration issue. But having no idea on how to troubleshoot.  This issue only appears in Tokyo region, while the SSM Quick Start website layout is different from what we see in HongKong region.

Answer

Have you reviewed Systems Manager agent logs? It is available under %PROGRAMDATA%\Amazon\SSM\Logs\ for Windows. Also, I recommend taking a look at[ this troubleshooting article](https://aws.amazon.com/premiumsupport/knowledge-center/systems-manager-ec2-instance-not-appear).

- [Viewing SSM Agent logs](https://docs.aws.amazon.com/systems-manager/latest/userguide/sysman-agent-logs.html)
- [Why is my EC2 instance not appearing under Managed Instances in the Systems Manager console?](https://aws.amazon.com/premiumsupport/knowledge-center/systems-manager-ec2-instance-not-appear)

SSM agent service failed to start on windows-server 2019 (datacenter)

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