You are presented with this error when starting up your K2 Service:
"Error","System","2001","ServerStartError","SourceCode.Hosting.Server.Runtime.HostServerEngine.StartHostServer","2001 Error Starting Host Server: System.Data.SqlClient.SqlException (0x80131904): Incorrect syntax near 'INDEX'. If this is intended as a part of a table hint, A WITH keyword and parenthesis are now required. See SQL Server Books Online for proper syntax.
This issue will occur after installing K2 5.2 Fix Pack 8.
In the K2 Hostserver log files, you may notice the following, which confirms you are facing the issue in question:
at SourceCode.Sync.Runtime.SyncService.Init(IServiceMarshalling serviceMarshalling, IServerMarshaling serverMarshaling)
at SourceCode.Hosting.Server.Runtime.HostServerEngine.EnrollHostableTypeInstance(IHostableType HostableTypeInstance)
at SourceCode.Hosting.Server.Runtime.HostTypeLoader.InitAndEnrollHostableType(String HostedTypeName, String InterfaceName)
at SourceCode.Hosting.Server.Runtime.HostTypeLoader.InitAndEnrollHostableTypes(String InterfaceName)
In K2 Five, only SQL 2014 and onwards is supported: https://help.k2.com/k2compatibilitysupportmatrix#SQLServer
The reason the issue occurs is because the server has SQL 2012 or lower installed. We advise you to install SQL 2014 when installing K2 Five.
However, if you have already run into the issue, please install the latest K2 5.2 Fix Pack to rectify the issue: https://help.k2.com/kb002760