Fail to run the dashboard on azure container apps

[mastoj]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I try to deploy aspire dashboard to container apps, but blazor fails to establis a connection. The request /_blazor?id=I5yPymIe9IPwna5zMGN5jQ&_=1731140445714 gives a 404.

I also get a lot of error messages

Error: Failed to start the transport 'WebSockets': Error: WebSocket failed to connect. The connection could not be found on the server, either the endpoint may not be a SignalR endpoint, the connection ID is not present on the server, or there is a proxy blocking WebSockets. If you have multiple servers check that sticky sessions are enabled.

Error: Failed to start the transport 'LongPolling': Error: No Connection with that ID: Status code '404'

Error: Failed to start the connection: Error: Unable to connect to the server with any of the available transports. Error: WebSockets failed: Error: WebSocket failed to connect. The connection could not be found on the server, either the endpoint may not be a SignalR endpoint, the connection ID is not present on the server, or there is a proxy blocking WebSockets. If you have multiple servers check that sticky sessions are enabled. ServerSentEvents failed: Error: 'ServerSentEvents' does not support Binary. Error: LongPolling failed: Error: No Connection with that ID: Status code '404'

I'm pretty sure they are related.

Expected Behavior

The dashboard to start.

Steps To Reproduce

I created the container app with the following commands. It is just for development/proof of concept that is why I allow anonymous access.

az containerapp create
--name $APP_NAME
--resource-group $AZ_RESOURCE_GROUP
--environment $AZ_CONTAINER_APP_ENV
--image mcr.microsoft.com/dotnet/aspire-dashboard:8.1.0
--target-port 18888
--ingress external
--query properties.configuration.ingress.fqdn

az containerapp update
--name $APP_NAME
--resource-group $AZ_RESOURCE_GROUP
--set-env-vars "DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS=true"

Exceptions (if any)

No response

.NET Version info

No response

Anything else?

No response