Why do I get an error while uploading images to the Sitecore image library

Paramter null error in Sitecore when using Visual Studio 2013

Posted by Michael Sundstrøm on 2015-05-12 15:17

Yesterday I saw this error in Sitecore 8. 

{% asset_img “Parameter-null-error.png” “Parameter null error” %}

[ArgumentNullException: Value cannot be null. Parameter name: key] System.Collections.Generic.Dictionary2.FindEntry(TKey key) +14370237</span> <span style="font-family: 'courier new', courier; font-size: x-small;">System.Collections.Generic.Dictionary2.TryGetValue(TKey key, TValue& value) +20 Microsoft.VisualStudio.Web.PageInspector.Runtime.WebForms.SelectionMappingRenderTraceListener   .GetLiteralTraceData(LiteralControl literal, TraceData& data) +71 Microsoft.VisualStudio.Web.PageInspector.Runtime.WebForms.SelectionMappingRenderTraceListener   .GetTraceData(Object renderedObject) +223 Microsoft.VisualStudio.Web.PageInspector.Runtime.WebForms.SelectionMappingRenderTraceListener   .EndRendering(TextWriter writer, Object renderedObject) +47

Being the first time I am running a project on Sitecore 8 I feared the product had died on me :(

This seem to be caused by an error in Visual Studio 2013

Simply adding this guy to webconfig app settings solves the problem

**<add key="PageInspector:ServerCodeMappingSupport" value="Disabled"/>**

Thanks to Alexander Sharamok for pointing me in the right direction.