Getting 404-exception when connecting to Qlik Sense Server with .NET-api

[daniellw]

Hello community,

i'm using the qlik sense .net API to connect to a qlik sense server. 

When using the version 13.8 of the api, the connection works. When updating to version 15.3 of the sdk, i get an WebSocketException: Connection with the remote server could not be established (inner exception WebException: (404) not found).

The same code is used in both cases, and exactly the same server uri and app id.

Example:

qLoc = Qlik.Engine.Location.FromUri("https://qsserver/hub:443");
qLoc.AsNtlmUserViaProxyAsync(true, null, false).Wait();
qAppId = Qlik.Engine.LocationExtensions.AppWithId(qLoc, "guid", true);

Exceptions are thrown in the last line.

What could cause this connection failure with the newer version? 

Thank you for any help!