Uncaught Error: Sys.ArgumentException: Cannot deserialize. The data does not correspond to valid JSON. Parameter name: data

[Itai]

Hi

I use ComboBox and I get this error sometimes:

Uncaught Error: Sys.ArgumentException: Cannot deserialize. The data does not correspond to valid JSON. Parameter name: data.

 

My Code:

  <telerik:radcombobox runat="server" id="ImpersonationRequestUsersCmb" height="190px" width="300px"
            markfirstmatch="true" enableloadondemand="true" highlighttemplateditems="true" emptymessage="<%$ Resources:UserImpersonationResources, SelectUserMessage %>"
            onclientitemsrequested="UpdateItemCountField" onitemsrequested="ImpersonationRequestUsersCmb_ItemsRequested"
            onitemdatabound="ComboBox_ItemDataBound" skin="MetroTouch"  dropdownwidth="500px" nowrap="True">
            <HeaderTemplate>
            </HeaderTemplate>
            <ItemTemplate>
                <ul> 
                    <li class="col1">
                        <%# (string.IsNullOrWhiteSpace((string)DataBinder.Eval(Container.DataItem, "Login"))) ? "&nbsp;" : DataBinder.Eval(Container.DataItem, "Login") %></li>
                    <li class="col2">
                        <%# (string.IsNullOrWhiteSpace((string)DataBinder.Eval(Container.DataItem, "FullName"))) ? "&nbsp;" : DataBinder.Eval(Container.DataItem, "FullName")%></li>
                    <li class="col3">
                        <%# DataBinder.Eval(Container.DataItem, "Email") %></li>
                </ul>
            </ItemTemplate>
            <FooterTemplate>
                <asp:Literal ID="ltStartString" runat="server" Text="<%$ Resources:UserImpersonationResources, TotalItemsString%>" />
                <asp:Literal runat="server" ID="ImpersonationListItemsCount" />
                <asp:Literal ID="ltEndString" runat="server" Text="<%$ Resources:UserImpersonationResources, ItemsString%>" />
            </FooterTemplate>
        </telerik:radcombobox>

 

 

please advise