从7.1升级到7.2(版本)后发布整个网站时出现问题

我们已经将sitecore版本从7.1升级到7.2,现在是发布整个网站的最后一步。当我们试图发布整个网站时,我们遇到了以下错误:

Job started: Publish to 'web'|#Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Exception: Could not resolve type name: Sitecore.Publishing.Pipelines.Publish.OverridePublishContext, Sitecore.Kernel (method: Sitecore.Configuration.Factory.CreateType(XmlNode configNode, String[] parameters, Boolean assert)).
   at Sitecore.Diagnostics.Error.Raise(String error, String method)
   at Sitecore.Configuration.Factory.CreateType(XmlNode configNode, String[] parameters, Boolean assert)
   at Sitecore.Configuration.Factory.CreateFromTypeName(XmlNode configNode, String[] parameters, Boolean assert)
   at Sitecore.Configuration.Factory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper)
   at Sitecore.Pipelines.CorePipelineFactory.GetObjectFromType(String type, XmlNode processorNode)
   at Sitecore.Pipelines.CoreProcessor.GetMethod(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Publishing.Pipelines.Publish.PublishPipeline.Run(PublishContext context)
   at Sitecore.Publishing.Publisher.Publish()
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.MethodBase.Invoke(`enter code here`Object obj, Object[] parameters)
   at (Object , Object[] )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Jobs.Job.ThreadEntry(Object state)