Object reference not set to an instance of an object.

[NullReferenceException: Object reference not set to an instance of an object.]
   Nop.Core.Plugins.PluginManager.PerformFileDeploy(FileInfo plug) +12
   Nop.Core.Plugins.PluginManager.Initialize() +1126

[Exception: Plugin 'USPS (US Postal Service)'. Object reference not set to an instance of an object.]
   Nop.Core.Plugins.PluginManager.Initialize() +2029

[Exception: Plugin 'USPS (US Postal Service)'. Object reference not set to an instance of an object.
Object reference not set to an instance of an object.
]
   Nop.Core.Plugins.PluginManager.Initialize() +2437

[InvalidOperationException: The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Plugin 'USPS (US Postal Service)'. Object reference not set to an instance of an object.
Object reference not set to an instance of an object.
.]
   System.Web.Compilation.BuildManager.InvokePreStartInitMethodsCore(ICollection`1 methods, Func`1 setHostingEnvironmentCultures) +613
   System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +141
   System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +102
   System.Web.Compilation.BuildManager.ExecutePreAppStart() +157
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +531

[HttpException (0x80004005): The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Plugin 'USPS (US Postal Service)'. Object reference not set to an instance of an object.
Object reference not set to an instance of an object.
.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9946132
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +90
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +261