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Home > Success Center > Netflow Traffic Analyzer (NTA) > NTA - Knowledgebase Articles > NTA 4.2.1 Service stops due to a missing SolarWinds.Orion.Core.Models.dll file

NTA 4.2.1 Service stops due to a missing SolarWinds.Orion.Core.Models.dll file

Updated March 19, 2018


This article describes an issue where the NetFlow service stops on the polling engine after a minute or two.

If you check the NTA Business Layer log in C:\ProgramData\SolarWinds\Logs\NTA\NTA.BusinessLayer.log, you see the following error:

ERROR SolarWinds.Orion.NetFlow.Service.Program - 
NetFlowService will be abnormally terminated - Unhandled exception.
System.TypeInitializationException: The type initializer for 
threw an exception. ---> System.IO.FileNotFoundException: Could not load file or 
 'SolarWinds.Orion.Core.Models, Version=2017.1.5300.1840, Culture=neutral, 
 PublicKeyToken=null' or one of its dependencies. The system cannot find the file 
   at System.Reflection.Emit.TypeBuilder.TermCreateClass(RuntimeModule module, 
   Int32 tk, ObjectHandleOnStack type)
   at System.Reflection.Emit.TypeBuilder.CreateTypeNoLock()
   at System.Reflection.Emit.TypeBuilder.CreateType()
   at Castle.DynamicProxy.Generators.Emitters.AbstractTypeEmitter.CreateType
   (TypeBuilder type)
   at Castle.DynamicProxy.Generators.Emitters.AbstractTypeEmitter.BuildType()
   at Castle.DynamicProxy.Generators.InterfaceProxyWithoutTargetGenerator.GenerateType
   (String typeName, Type proxyTargetType, Type[] interfaces, INamingScope namingScope)
   at Castle.DynamicProxy.Generators.InterfaceProxyWithTargetGenerator.
   <>c__DisplayClass1.<GenerateCode>b__0(String n, INamingScope s)
   at Castle.DynamicProxy.Generators.BaseProxyGenerator.ObtainProxyType
   (CacheKey cacheKey, Func`3 factory)
   at Castle.DynamicProxy.ProxyGenerator.CreateInterfaceProxyWithoutTarget
   (Type interfaceToProxy, Type[] additionalInterfacesToProxy, ProxyGenerationOptions 
   options, IInterceptor[] interceptors)
   at Castle.DynamicProxy.ProxyGenerator.CreateInterfaceProxyWithoutTarget
   (Type interfaceToProxy, IInterceptor interceptor)
   at SolarWinds.Orion.Core.Common.Proxy.BusinessLayer.CoreBusinessLayerProxyPoolCreator


  • NTA 4.2.1


The file SolarWinds.Orion.Core.Models.dll is probably missing in the NTA directory.


  1. Browse to C:\Program Files (x86)\SolarWinds\Orion\NetFlowTrafficAnalysis, and see if you locate the file SolarWinds.Orion.Core.Models.dll.
  2. If it exists, backup the file to your desktop. 
  3. Browse to C:\Program Files (x86)\SolarWinds\Orion\SolarWinds.Orion.Core.Models.dll and copy the file.
  4. Paste it into the NTA directory C:\Program Files (x86)\SolarWinds\Orion\NetFlowTrafficAnalysis.


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