Blazor in Azure: The list of component records is not valid

Question

When deploying our blazor app to azure, it fails four out of five times with this error (copied from chrome dev tools):

[2019-12-16T11:12:55.214Z] Information: Normalizing '_blazor' to 'https://example.com/_blazor'.
[2019-12-16T11:12:55.470Z] Information: WebSocket connected to wss://example-web-signalr-service.service.signalr.net/client/?hub=componenthub&asrs.op=%2F_blazor&negotiateVersion=1&asrs_request_id=...&id=...&access_token=...
[2019-12-16T11:12:55.548Z] Error: The list of component records is not valid.
    e.log @ blazor.server.js:15
    C @ blazor.server.js:8
    (anonymous) @ blazor.server.js:8
    (anonymous) @ blazor.server.js:1
    e.invokeClientMethod @ blazor.server.js:1
    e.processIncomingData @ blazor.server.js:1
    connection.onreceive @ blazor.server.js:1
    i.onmessage @ blazor.server.js:1
[2019-12-16T11:12:55.552Z] Information: Connection disconnected.
Uncaught (in promise) Error: Invocation canceled due to the underlying connection being closed.
    at e.connectionClosed (blazor.server.js:1)
    at e.connection.onclose (blazor.server.js:1)
    at e.stopConnection (blazor.server.js:1)
    at e.transport.onclose (blazor.server.js:1)
    at e.close (blazor.server.js:1)
    at e.stop (blazor.server.js:1)
    at e.<anonymous> (blazor.server.js:1)
    at blazor.server.js:1
    at Object.next (blazor.server.js:1)
    at a (blazor.server.js:1)

We can't make any sense out of this. What might be the cause for blazor to fail like this? Why doesn't it fail on our local developer machines? It is hard to find anything about this in google.

Please tell me if I need to provide more information. I am not sure which code snippets might be useful information.

Answer 1

try this:

services.AddSignalR().AddAzureSignalR(options =>
{
    options.ServerStickyMode = Microsoft.Azure.SignalR.ServerStickyMode.Required;
});