Configuring maximum number of simultaneous open WebSockets (for IE)

Given I’ve got this JS application. All client side JS communicating using web sockets. One page may have multiple web sockets open as many as 10-15.

Firefox and Chrome handle this many open web sockets at once just fine. IE11 seemed to have a limitation of 6 open web sockets at once.

Once I open that 7th web socket, regardless of socket call to the third-party server, I got an error thrown by IE, which closes the socket and gives the general error “SecurityError” and expanding the __proto__ section it gives me . The error seems to be pretty generic.

At first it looks as if there may be a trusted zone type issue with IE, but even after adding the client site to trusted zone as well as the server providing the data, the error still persisted.


This site shows the max connections settings for IE. It’s a registry setting in Windows that controls the amount of web socket connections.

Interestingly enough, By default, windows doesn’t have that registry key, but there is still a limit. Therefore you have to add the Registry in order for this to work.

The MSDN Section mentions:

WebSocket Maximum Server Connections

Internet Explorer 10. When enabled, the FEATURE_WEBSOCKET_MAXCONNECTIONSPERSERVER feature sets the maximum number of concurrent WebSocket connections allowed to a single host. The minimum number that can be specified is 2 and the maximum value allowed is 128.

The default value for this setting is 6 in Internet Explorer and applications hosting the WebBrowser Control. To modify this feature by using the registry, add the name of your executable file to the following setting.

         Internet Explorer
                     contoso.exe = (DWORD) 0x00000006 (6)

This should fix the problem.