Validasi kondisi tampilan MAC gagal.

Hai teman,
saya sedang bekerja di sebuah proyek. saya telah menyelesaikan proyek itu ketika saya membuka proyek ini empat hari kemudian saya mengalami kesalahan.

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. 

dalam proyek ini saya tidak pernah menggunakan Enkripsi apa pun untuk validasi. ketika saya melalui internet saya tidak melihat ada situs yang meminta saya untuk mengaturnya

<pages enableEventValidation="false" viewStateEncryptionMode ="Never" />

dalam file konfigurasi web. bahkan setelah saya melakukan ini saya masih mendapatkan kesalahan. kesalahan ini terjadi ketika saya mengambil data dari database dan menampilkannya di tampilan grid. apa yang harus saya ingin lakukan.
di bawah file webconfig saya.

<?xml version="1.0"?>
<configuration>
    <configSections>
        <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
            <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
                <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false"/>
                <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
                    <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false"/>
                    <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false"/>
                    <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false"/>

                </sectionGroup>
            </sectionGroup>
        </sectionGroup>
    </configSections>
    <system.web>
        <pages>
            <controls>
                <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            </controls>
            <tagMapping>
                <add tagType="System.Web.UI.WebControls.CompareValidator" mappedTagType="System.Web.UI.Compatibility.CompareValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add tagType="System.Web.UI.WebControls.CustomValidator" mappedTagType="System.Web.UI.Compatibility.CustomValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add tagType="System.Web.UI.WebControls.RangeValidator" mappedTagType="System.Web.UI.Compatibility.RangeValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add tagType="System.Web.UI.WebControls.RegularExpressionValidator" mappedTagType="System.Web.UI.Compatibility.RegularExpressionValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add tagType="System.Web.UI.WebControls.RequiredFieldValidator" mappedTagType="System.Web.UI.Compatibility.RequiredFieldValidator, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add tagType="System.Web.UI.WebControls.ValidationSummary" mappedTagType="System.Web.UI.Compatibility.ValidationSummary, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            </tagMapping>
        </pages>
        
        <compilation debug="true">
            <assemblies>
                <add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
                <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
                <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
                <add assembly="MySql.Data, Version=6.2.3.0, Culture=neutral, PublicKeyToken=C5687FC88969C44D"/></assemblies>
        </compilation>
        <httpHandlers>
            <remove verb="*" path="*.asmx"/>
            <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>
        </httpHandlers>
        <httpModules>
            <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </httpModules>
    </system.web>
    <system.web.extensions>
        <scripting>
            <webServices>
                <!-- Uncomment this line to customize maxJsonLength and add a custom converter -->
                <!--
      <jsonSerialization maxJsonLength="500">
        <converters>
          <add name="ConvertMe" type="Acme.SubAcme.ConvertMeTypeConverter"/>
        </converters>
      </jsonSerialization>
      -->
                
            </webServices>
            <!--
      <scriptResourceHandler enableCompression="true" enableCaching="true" />
      -->
        </scripting>
    </system.web.extensions>
    <system.webServer>
        <validation validateIntegratedModeConfiguration="false"/>
        <modules>
            <add name="ScriptModule" preCondition="integratedMode" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </modules>
        <handlers>
            <remove name="WebServiceHandlerFactory-ISAPI-2.0"/>
            <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            <add name="ScriptResource" verb="GET" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </handlers>
    </system.webServer>
</configuration>