An item with the same key has already been added

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<!DOCTYPE html>
↵<html>
↵    <head>
↵        <title>An item with the same key has already been added.</title>
↵        <meta name="viewport" content="width=device-width" />
↵        <style>
↵         body {font-family:"Verdana";font-weight:normal;font-size: .7em;color:black;} 
↵         p {font-family:"Verdana";font-weight:normal;color:black;margin-top: -5px}
↵         b {font-family:"Verdana";font-weight:bold;color:black;margin-top: -5px}
↵         H1 { font-family:"Verdana";font-weight:normal;font-size:18pt;color:red }
↵         H2 { font-family:"Verdana";font-weight:normal;font-size:14pt;color:maroon }
↵         pre {font-family:"Consolas","Lucida Console",Monospace;font-size:11pt;margin:0;padding:0.5em;line-height:14pt}
↵         .marker {font-weight: bold; color: black;text-decoration: none;}
↵         .version {color: gray;}
↵         .error {margin-bottom: 10px;}
↵         .expandable { text-decoration:underline; font-weight:bold; color:navy; cursor:pointer; }
↵         @media screen and (max-width: 639px) {
↵          pre { width: 440px; overflow: auto; white-space: pre-wrap; word-wrap: break-word; }
↵         }
↵         @media screen and (max-width: 479px) {
↵          pre { width: 280px; }
↵         }
↵        </style>
↵    </head>
↵
↵    <body bgcolor="white">
↵
↵            <span><H1>Server Error in '/' Application.<hr width=100% size=1 color=silver></H1>
↵
↵            <h2> An item with the same key has already been added. </h2></span>
↵
↵            <font face="Arial, Helvetica, Geneva, SunSans-Regular, sans-serif ">
↵
↵             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.
↵
↵            <br><br>
↵
↵             Exception Details: System.ArgumentException: An item with the same key has already been added.<br><br>
↵
↵            Source Error: <br><br>
↵
↵            <table width=100% bgcolor="#ffffcc">
↵               <tr>
↵                  <td>
↵                      <code>
↵
↵An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.                      </code>
↵
↵                  </td>
↵               </tr>
↵            </table>
↵
↵            <br>
↵
↵            Stack Trace: <br><br>
↵
↵            <table width=100% bgcolor="#ffffcc">
↵               <tr>
↵                  <td>
↵                      <code><pre>
↵
↵[ArgumentException: An item with the same key has already been added.]
↵   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +56
↵   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +12946796
↵   System.Collections.Generic.CollectionExtensions.ToDictionaryFast(TValue[] array, Func`2 keySelector, IEqualityComparer`1 comparer) +116
↵   System.Web.Mvc.ModelBindingContext.get_PropertyMetadata() +149
↵   System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +176
↵   System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +101
↵   System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +55
↵   System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +1209
↵   System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +333
↵   System.Web.Mvc.DefaultModelBinder.GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) +17
↵   System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor) +377
↵   System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext controllerContext, ModelBindingContext bindingContext) +101
↵   System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Object model) +55
↵   System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +1209
↵   System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) +333
↵   System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +336
↵   System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +105
↵   System.Web.Mvc.Async.<>c__DisplayClass3_1.<BeginInvokeAction>b__0(AsyncCallback asyncCallback, Object asyncState) +640
↵   System.Web.Mvc.Async.WrappedAsyncResult`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +14
↵   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +128
↵   System.Web.Mvc.Async.AsyncControllerActionInvoker.BeginInvokeAction(ControllerContext controllerContext, String actionName, AsyncCallback callback, Object state) +346
↵   System.Web.Mvc.<>c.<BeginExecuteCore>b__152_0(AsyncCallback asyncCallback, Object asyncState, ExecuteCoreState innerState) +27
↵   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +30
↵   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +128
↵   System.Web.Mvc.Controller.BeginExecuteCore(AsyncCallback callback, Object state) +494
↵   System.Web.Mvc.<>c.<BeginExecute>b__151_1(AsyncCallback asyncCallback, Object callbackState, Controller controller) +16
↵   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +20
↵   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +128
↵   System.Web.Mvc.Controller.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) +403
↵   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.BeginExecute(RequestContext requestContext, AsyncCallback callback, Object state) +16
↵   System.Web.Mvc.<>c.<BeginProcessRequest>b__20_0(AsyncCallback asyncCallback, Object asyncState, ProcessRequestState innerState) +54
↵   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState) +30
↵   System.Web.Mvc.Async.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout) +128
↵   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +427
↵   System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +48
↵   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +16
↵   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +444
↵   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +132
↵   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +163
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↵ Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4001.0
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I had tried to cal ajax post method like

JavaScript

$.ajax({
url:'/Cart/cartmodel',
type:'POST',
data:json.stringfy(data),
ContentType:'application/json;charset=utf-8',
Success:function(result){

}
error:function(JqXHR,Status,thrownerror){
var response=jquery.ParseJson(JqXHR.reponsetext)
}

});

I don't have duplication properties on modal

What I have tried:

An item with the same key has already been added

Posted 29-Jan-21 3:20am

Ramesh p

Updated 29-Jan-21 4:01am

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

thatraja · Answer 1 · 2021-01-29T04:01:00

Solution 1

It's impossible to guess, without seeing code-behind. But below thread has 20+ answers for this error message. So check those & make changes in your code.

asp.net mvc - An item with the same key has already been added - Stack Overflow[^]

Posted 29-Jan-21 4:01am

thatraja