SignalR connection breaks when using window.print() in browser

[cool-akash]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When calling window.print() from the client while connected to a SignalR hub, the SignalR connection closes unexpectedly.

It seems that window.print() freezes the browser UI thread, which prevents the client heartbeat/ping from being processed. As a result, SignalR considers the client unresponsive and closes the connection.

Environment:

• ASP.NET Core (SignalR)
• SignalR JavaScript client (browser)
• Browser: Chrome/Edge (latest)

Expected Behavior

Expected Behavior:

• The SignalR connection should remain stable during/after the print dialog is open.
• Heartbeats should ideally tolerate temporary UI thread blocking.

Actual Behavior:

• While the print dialog is open, no pings are sent.
• After the ClientTimeoutInterval elapses, the connection closes with error:

Steps To Reproduce

Steps to Reproduce:

1. Start a simple SignalR hub with default options:
   services.AddSignalR(options =>
   {
   options.EnableDetailedErrors = true;
   options.HandshakeTimeout = TimeSpan.FromSeconds(60);
   options.KeepAliveInterval = TimeSpan.FromSeconds(15);
   options.ClientTimeoutInterval = TimeSpan.FromSeconds(50);
   });

2. Connect a JavaScript client in the browser.

3. While connected, trigger a window.print() call.
   setTimeout(() => {
   window.print();
   }, 0);

4.Observe network traffic and logs.

Exceptions (if any)

Connection closed with an error.
OperationCanceledException: Client hasn't sent a message/ping within the configured ClientTimeoutInterval.

Log
"type":7,"error":"Connection closed with an error. OperationCanceledException: Client hasn't sent a message/ping within the configured ClientTimeoutInterval.","allowReconnect":true

.NET Version

8

Anything else?

[cool-akash]

This is currently affecting a deliverable on my end, so I would greatly appreciate it if this could be reviewed and addressed at the earliest possible convenience.