I recently put a site into production environment and am regularly getting the following Server Error.

Can anybody shed some light on what this could be?

• Umbraco version 7.3.3 assembly: 1.0.5813.17867
• SEO Checker 1.9.4
• Hosted on Azure

Here's the stack trace

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

The source code that generated this unhandled exception can only be shown when compiled in debug mode. To enable this, please follow one of the below steps, then request the URL:

1. Add a "Debug=true" directive at the top of the file that generated the error. Example:

  <%@ Page Language="C#" Debug="true" %>

or:

2) Add the following section to the configuration file of your application:

<configuration>

   <system.web>

       <compilation debug="true"/>

   </system.web>

</configuration>

Note that this second technique will cause all files within a given application to be compiled in debug mode. The first technique will cause only that particular file to be compiled in debug mode.

Important: Running applications in debug mode does incur a memory/performance overhead. You should make sure that an application has debugging disabled before deploying into production scenario.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
  SEOChecker.Core.Config.Configuration.(String , String ) +98
  SEOChecker.Core.Umbraco.DocumentWrappers.UmbracoDocument.get_SEOConfiguration() +85
  SEOChecker.Core.Extensions.UmbracoDocumentExtensions.RobotsIndexOption(IUmbracoDocument doc, SEOCheckerMetaRobotValues robotDataTypeValues) +35
  SEOChecker.Library.MetaData.get_Robots() +50
  ASP._Page_Views_Master_cshtml.Execute() +2031
  System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +198
  System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
  System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +90
  System.Web.WebPages.<>c__DisplayClass3.<RenderPageCore>b__2(TextWriter writer) +232
  System.Web.WebPages.HelperResult.WriteTo(TextWriter writer) +10
  System.Web.WebPages.WebPageBase.Write(HelperResult result) +80
  System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action`1 body) +63
  System.Web.WebPages.WebPageBase.PopContext() +237
  System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +98
  System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +256
  System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
  Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer) +113
  System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +291
  System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
  System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
  System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
  System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
  System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
  System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +173
  System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
  System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
  System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
  System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
  System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
  System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
  System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
  System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
  System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
  System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
  System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
  System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
  System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
  System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
  System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
  System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +545
  System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.6.114.0