how to remove Error Invalid postback or callback argument. Event validation is enabled in visual studio

<system.web>
    <pages validateRequest="false" enableEventValidation="false" />
<compilation debug="true" targetFramework="4.5">
<assemblies>
       
<add assembly="CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.Shared, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.ReportSource, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.ReportAppServer.Controllers, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.ReportAppServer.DataDefModel, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.CrystalReports.Engine, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304" />
<add assembly="CrystalDecisions.ReportAppServer.ClientDoc, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
</assemblies>
</compilation>
<httpRuntime targetFramework="4.5" />
<httpHandlers>
<add verb="GET" path="CrystalImageHandler.aspx" type="CrystalDecisions.Web.CrystalImageHandler, CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" />
</httpHandlers>
    <sessionState timeout="999"/>
    <customErrors mode="Off"/>
</system.web>