Aspire Dashboard gRPC Error Caused by a Local Proxy

I have been working with Aspire in a couple of projects lately. Suddenly I started getting this exception every time I tried to get into the dashboard:

fail: Aspire.Hosting.Dashboard.ServiceClient.DashboardClient[0]
      Error #4 watching interactions.
      Grpc.Core.RpcException: Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.", DebugException="System.Net.Http.HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.")
       ---> System.Net.Http.HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.
         at System.Net.Http.HttpConnectionPool.ThrowGetVersionException(HttpRequestMessage request, Int32 desiredVersion, Exception inner)
         at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
         at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
         at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
         at Grpc.Net.Client.Balancer.Internal.BalancerHttpHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
         at Grpc.Net.Client.Internal.GrpcCall`2.RunCall(HttpRequestMessage request, Nullable`1 timeout)
         --- End of inner exception stack trace ---
         at Grpc.Net.Client.Internal.GrpcCall`2.GetResponseHeadersCoreAsync()
         at Grpc.Net.Client.Internal.Retry.RetryCallBase`2.GetResponseHeadersCoreAsync()
Aspire.Hosting.Dashboard.ServiceClient.DashboardClient: Error: Error #4 watching interactions.
Grpc.Core.RpcException: Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.", DebugException="System.Net.Http.HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.")
 ---> System.Net.Http.HttpRequestException: Requesting HTTP version 2.0 with version policy RequestVersionExact while unable to establish HTTP/2 connection.
   at System.Net.Http.HttpConnectionPool.ThrowGetVersionException(HttpRequestMessage request, Int32 desiredVersion, Exception inner)
   at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at Grpc.Net.Client.Balancer.Internal.BalancerHttpHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at Grpc.Net.Client.Internal.GrpcCall`2.RunCall(HttpRequestMessage request, Nullable`1 timeout)
   --- End of inner exception stack trace ---
   at Grpc.Net.Client.Internal.GrpcCall`2.GetResponseHeadersCoreAsync()
   at Grpc.Net.Client.Internal.Retry.RetryCallBase`2.GetResponseHeadersCoreAsync()
   at Aspire.Dashboard.ServiceClient.DashboardClient.IsUnimplemented(AsyncDuplexStreamingCall`2 call) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 511
   at Aspire.Dashboard.ServiceClient.DashboardClient.WatchInteractionsAsync(RetryContext retryContext, CancellationToken cancellationToken) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 437
   at Aspire.Dashboard.ServiceClient.DashboardClient.WatchWithRecoveryAsync(Func`3 action, String actionName, CancellationToken cancellationToken) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 321
         at Aspire.Dashboard.ServiceClient.DashboardClient.IsUnimplemented(AsyncDuplexStreamingCall`2 call) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 511
         at Aspire.Dashboard.ServiceClient.DashboardClient.WatchInteractionsAsync(RetryContext retryContext, CancellationToken cancellationToken) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 437
         at Aspire.Dashboard.ServiceClient.DashboardClient.WatchWithRecoveryAsync(Func`3 action, String actionName, CancellationToken cancellationToken) in /_/src/Aspire.Dashboard/ServiceClient/DashboardClient.cs:line 321

This error seemed to occur whenever I attempted to connect my API and frontend, so it seemed to have something to do with network calls.

These days, working with AI, I naturally let both GitHub Copilot (with various models) and ChatGPT Codex have its go on this error. No AI actually managed to solve the issue, but I got one key signal when one of them told me there might be a proxy issue.

It occurred to me that I’m using Freedom to avoid distractions when I’m working, and this actually uses a proxy to block web sites and all. So to solve the exceptions, and get Aspire working again, I needed to add localhost as an exception to the proxy.

On MacOS, this is as simple as clicking the Freedom icon, and “Enable website Exceptions”. Screen shot of Freedom menu options

Next you will also need to add the actual exception, which can be done by clicking the same icon, and then click “Manage website exceptions”. This will open a popup window, where you can add localhost and 127.0.0.1. (SCREENSHOT HERE) Screen shot of Freedom add exception websites

Keep in mind that this will only be available to edit outside of a focus session.