Symptoms

Unable to start the server successfully. 00:16:02","Error","System","2001","ServerStartError","SourceCode.Hosting.Server.Runtime.HostServerEngine.StartHostServer","2001 ""2062156","2017-01-24 00:55:10","Error","System","2001","ServerStartError","SourceCode.Hosting.Server.Runtime.HostServerEngine.StartHostServer","2001 Error Starting Host Server: Invalid URI: The format of the URI could not be determined.","system","10.155.143.191","CTSC00649007701:C:Program Files (x86)K2 blackpearl47Host ServerBin","2062156","fe531c580f384cbab0cc109ff21bf5cc","""
 

Diagnoses

The issue was caused by missing "https://" in EWS ConnectionString URL.
 

Resolution

Using ConnectionStringEditor, we were able to edit and correct the EWS ConnectionStrings, and that resolved the issue.