Symptoms

After upgrade K2 4.6.7 -> 4.6.8 we are facing issue opening K2 for SharePoint app in ribbon in SharePoint 2013. Below error occurs:
Error Receiving Buffer:An existing connection was forcibly closed by the remote host
•Type: SourceCode.SmartObjects.Client.SmartObjectException
•Source: SourceCode.SmartObjects.Client
•Method Base
◦Member Type: Method
◦Name: ExecuteScalar
◦Module
■Scope Name: SourceCode.SmartObjects.Client.dll
◦Declaring Type
■Full Name: SourceCode.SmartObjects.Client.SmartObjectClientServer
•Stack Trace: at SourceCode.SmartObjects.Client.SmartObjectClientServer.ExecuteScalar(SmartObject smartObject, DataTable inputTable)at SourceCode.Forms.AppFramework.FormRuntime.SmartObjectExecution(XPathNavigator nav, Boolean outputDependencies, SmartObjectClientServer svr)at SourceCode.Forms.AppFramework.FormRuntime.WorkXmlToApi(String xml)at SourceCode.Forms.Runtime.AJAXCall.ProcessRequest(HttpContext context)

 

Diagnoses

The error received suggests that ports are not open or are in use.
Setting the correct configurations usually solves the problem
 

Resolution

All ports seems fine we checked every where but could not locate the source of the issue.
The problem started after the upgrade so something might have gone wrong with the configuration.
The client then did a reinstall of K2 and this resolved the issue.