Upgraded to Windows Admin Center 1910 and imported connections using the Import-Connection powershell module.

WAC will no longer load with error

500 - ArgumentException: An item with the same key has already been added.
Stack trace: at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add)
at Microsoft.ManagementExperience.FrontEnd.Controllers.NodeController.GetConnections()
at lambda_method(Closure , Object , Object[] )
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary2 arguments, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.ManagementExperience.FrontEnd.Handlers.ImpersonationActionInvoker.<InvokeActionAsync>d1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d1.MoveNext()

Running WAC in HA on Windows Server 2019. Upgraded using the MSFT powershell script for HA installation etc.

Checked import CSV and there were no duplicate servers in the file.

When attempting to add two new Windows Server 2019 nodes with nothing else besides updates and one Management IP, I get this error message:

server01.domain.com not found, or the provided credentials don’t have access. Verify the name and credentials are correct, check that server is up, and then click Refresh to try again.

I changed the credentials to a Domain Admin account, added the account manually to local Administrators and tried other accounts as well. I was able to add each server as standalone servers to Windows Admin Center but the issue is only when I try to create the cluster from within Windows Admin Center.

When deploying WAC on a Windows Server as the ‘Windows Admin Center’ Service you cannot access Internet Feeds for Extensions (e.g. https://aka.ms/sme-extension-feed) via a proxy server if the Server does not have direct access to the Internet. This means the user experience is diminished as new Extensions cannot downloaded via the Extensions section in WAC and / or existing extensions cannot be updated via the Extensions section.

It can be achieved by setting a proxy for the Network Service account that the WAC Service runs under, but that's not ideal.

Suggest adding the option to configure a proxy the ‘Internet Access’ section under settings. Users would need to be able to specify the proxy server address, port, and any credentials if authentication is used (but have the option to just anonymous access with no credentials)

Windows Admin Center installed on Windows 10 1909. Logged in with an account in Windows with standard user permissions. Right-click and run-as on Windows Admin Center and enter admin credentials. There is no process spawned running my admin credentials.

Launching Edge or Chromium Edge or Windows Admin Center with standard user credentials will launch the page just fine, but I receive an error trying to install any extensions for the Windows Admin Center with error message "Couldn't install the extension: 'Active Directory (Preview)'. Error: Access denied. Unable to perform requested operation. Administrative privilege is required."

The old version of Edge doesn't allow for run-as. Chromium Edge and Google Chrome browsers do allow for run-as, but fails to load the Windows Admin Center with those admin credentials with error "You are not authorized to view this page. If you recently updated Windows Admin Center, you may need to restart your browser, and then refresh the page."