I am currently building Non Production TFS 2015 environment. I am restoring database including DBs from production to the new QA DB instance. I performed DB restore using TFSRestore.exe. The restore work successfully.
In TFS QA then I install Application Tier and configure to TFS QA and TFS QA service account.
Then I did RemapDBs, Reset Owner, RegisterDB then start the service. Then I change the Notification URL to point to QA TFS Url.
What is strange is that I can see that in Applications Tiers, I can see 2 machine names display. One is TFS Prod machine and TFS QA Machine Name. How I can remove Production TFS machine name under Application Tier section.
I check the checkbox "Filter out machines that have not connected in more than 3 days"
After 3 days the TFS Prod machine is remove from the Application Tier section. Since I want to do inplace upgrade to the next version therefore is it safe to do this?, how do I know this would not impact the TFS Prod?
I did run the TFSConfig ChangeServerID /SQLInstance:SPTEST\Contoso /DatabaseName:Tfs_Configuration /ProjectCollectionsOnly
as result, it created new hostID (Guid Number) inside TFS_configuration.tbl_ServiceHost. However, when I select a project in Team Foundation Server I receive an error TF31001: Cannot connect to Team Foundation Server at Project1. The server returned the following error. Value cannot be null. Parameter name: service Definition
Resolve this by delete anything under cache folder c:\users[username]\Appdata\Local\Microsoft\Team Foundation\5.0\Cache
This is similar post https://social.msdn.microsoft.com/Forums/vstudio/en-US/0ba7caad-4210-4991-b6f0-d4f1dd8c409b/removing-application-tier-server
According to your description, your scenario should be Move or Clone Team Foundation Server from one hardware to another
(Clone option) Reconfigure server IDs and remap databases:
Perform the next set of steps on the new application-tier server if you intend to continue using the original TFS instance. These steps are necessary to avoid the risk of corruption of one or both deployments. If both servers are live, you could end up with corruption, particularly if they are pointing to the same SharePoint or reporting resources.
So, please try to Reconfigure server IDs and remap databases. If that still not work, I'm afriad that you have to remove the DB instance and reconfigure the QA envrionment step by step following the instruction mentioned here.
UPDATE:
Seems you just restored an application-tier server but not Move or Clone Team Foundation Server from one hardware to another
For restoring an application-tier server, the name of the old application-tier server remains there is expected (See the end of this article.).
Note: The name of the old application-tier server will still appear in the list of application-tier servers in the administration console for Team Foundation. If you select the Filter out machines that have not connected in more than 3 days check box, the old server will disappear from the list within three days.
So, to avoid showing the old App Tier machine name you need to follow the steps to Move or Clone Team Foundation Server from one hardware to another as I mentioned in the original answer.
Note: You must install but not configure TFS on the new data-tier server, and then use the restore function in the Scheduled Backups node