The RPC connection flow was different than expected

The connection to the datasource could not be established.
ADDITIONAL INFORMATION
The RPC connection flow was different than expected.
STACK TRACE
Exception: The RPC connection flow was different than expected.
at MailAndDeploy.Server.Connectors.QlikSense.Rpc.RpcConnection..ctor(IRpcConnectionInitiator pInitiator, String pUrl, RpcHeader[] pHeaders, RpcCookie[] pCookies, RpcAuthenticationMethod pAuthenticationMethod, NetworkCredential pCredentials, RpcConnectionResetSettings pResetSettings)
at MailAndDeploy.Server.Connectors.QlikSense.QsConnection.CreateRpcConnection(String pUrl, RpcHeader[] pHeaders, RpcCookie[] pCookies, RpcConnectionResetSettings pResetSettings)
at MailAndDeploy.Server.Connectors.QlikSense.QsConnection.OpenApp(String pAppId, String pEngineSessionId)
at MailAndDeploy.Server.Connectors.QlikSense.QlikSenseAppConnector.FromDatasource(QlikSenseAppDatasource pDatasource)
at MailAndDeploy.Server.Services.Management.Ui.DatasourcesSheet.ListPage_EntitiesTable_CellButtonClicked(String pSender, String pData)
Exception: Response 'OnAuthenticationInformation' or 'OnConnected' was expected, but 'OnMaxParallelSessionsExceeded' has been received. 

Please make sure that the M&D Service Account has a dedicated license. The M&D Service Account should not be the same one as the Qlik Sense Service Account.