Symptoms

User has been granted access to K2 Designer via IIS Authorization rules but unable to access K2 designer with the following error:

Server Error

Object reference not set to an instance of object.

Exception details:

at SourceCode.Forms.Default.Page_Load(Object sender, EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
 

Diagnoses

This most likely caused by some issue with client side cache and can be addressed by clearing IE cache and restarting it.

Try clearing browser cache + restarting your browser and trying to access designer once again. To clear browser cache in IE you can press Ctrl + Shift + Del while IE window is active, you may accept default settings and click on Delete button - once you get a popup that IE finishing deleting your data, restart IE.

If this doesn't help try to reboot your workstation just in case.
 

Resolution

Try clearing browser cache or restart client's workstation to resolve this.