Asp.net mvc Session[""]="xxx" gives Object reference not set to an instance of a-CodePudding

I am working on a project of ASP.NET MVC. I have used Session in controller.

It is working fine on my local. but it gives an error on server.

What should I do? for both local and live all files are same but only connection string is changed in web.config

also check my web.config file. what should I add?

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  https://go.microsoft.com/fwlink/?LinkId=301880
  -->
<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
  </configSections>
  <appSettings>
    <add key="webpages:Version" value="3.0.0.0" />
    <add key="webpages:Enabled" value="false" />
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
  </appSettings>
  <!--
    For a description of web.config changes see http://go.microsoft.com/fwlink/?LinkId=235367.

    The following attributes can be set on the <httpRuntime> tag.
      <system.Web>
        <httpRuntime targetFramework="4.7.2" />
      </system.Web>
  -->
  
   <system.web>
    <customErrors mode="Off" defaultRedirect="/404?error=1" redirectMode="ResponseRedirect">
    </customErrors>
    <compilation debug="true" targetFramework="4.7.2" />
    <httpRuntime targetFramework="4.6.1" maxRequestLength="2147483647" executionTimeout="1600" requestLengthDiskThreshold="2147483647" />
    <httpModules>
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" />
    </httpModules>
  
  </system.web>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" culture="neutral" publicKeyToken="30ad4fe6b2a6aeed" />
        <bindingRedirect oldVersion="0.0.0.0-13.0.0.0" newVersion="13.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="0.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Owin.Security" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="Microsoft.Owin" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-5.2.7.0" newVersion="5.2.7.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <modules>
      <remove name="ApplicationInsightsWebTracking" />
      <add name="ApplicationInsightsWebTracking" type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" preCondition="managedHandler" />
      <remove name="Session" />
      <add name="Session" type="System.Web.SessionState.SessionStateModule" />
    </modules>
  </system.webServer>
  <connectionStrings>
    <!--<add name="ConnectionStringName" connectionString="Data Source=ADMIN-PC\IRIPL;Initial Catalog=Mahendra_Revamp;Integrated Security=True;Max Pool Size=50000;Pooling=True;" />-->
    <!--<add name="ConnectionStringName" connectionString="Data Source=DESKTOP-EITB23B\SQLEXPRESS;Initial Catalog=Mahindra_Uat_Live_Copy;Integrated Security=True;Max Pool Size=50000;Pooling=True;" />-->

  <add name="Mahindra_Uat_Live_IdentityConnection" connectionString="Data Source=DESKTOP-EITB23B\SQLEXPRESS; Initial Catalog=Mahindra_Uat_Live;MultipleActiveResultSets=True;integrated security=True;" providerName="System.Data.SqlClient" />
  
  <!--<add name="Mahindra_Uat_Live_IdentityConnection" connectionString="datasource=DESKTOP-EITB23B\SQLEXPRESS;initial catalog=Mahindra_Uat_Live_Copy;integrated security=True;MultipleActiveResultSets=True;App=IdentitySample.Admin" providerName="System.Data.EntityClient" />-->
    <add name="Mahendra_RevampEntities" connectionString="metadata=res://*/Models.Model1.csdl|res://*/Models.Model1.ssdl|res://*/Models.Model1.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=DESKTOP-EITB23B\SQLEXPRESS;initial catalog=Mahindra_Uat_Live;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v13.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
  <system.codedom>
    <compilers>
      <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:1659;1699;1701" />
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer " />
    </compilers>
  </system.codedom>
</configuration>

CodePudding user response：

you have to put some validation in your code, at least you will know where is the error from

var dealerDetails=...your code
if (dealerDetails==null) return BadRequest("dealer is not found);
Session["DealerDetailsId"]=dealerDetails.Id;

you have to check your connection string and db permissions if you have this error only on some servers. Maybe you will have to ask your DBA for help or check a server logging

Run Event Viewer as administrator
Go to Windows Logs => Application