Error Logging and Management Handling in .NET is a technique by which errors are logged into database.

For doing this first you need to download DLL called Elmah.dll

Then write this code in your Web.Config file.

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="elmah">
      <section name="security" requirePermission="false"
    type="Elmah.SecuritySectionHandler, Elmah" />
      <section name="errorLog" requirePermission="false"
    type="Elmah.ErrorLogSectionHandler, Elmah" />
      <section name="errorMail" requirePermission="false"
    type="Elmah.ErrorMailSectionHandler, Elmah" />
      <section name="errorFilter" requirePermission="false"
    type="Elmah.ErrorFilterSectionHandler, Elmah" />
    </sectionGroup>
  </configSections>
  <connectionStrings>
    <add name="elmah-express" connectionString="Server=KAZOL-PC\SQLEXPRESS08;
    Database=Elmah&#95;Errorlog;Trusted&#95;Connection=Yes;" />
  </connectionStrings>
  <elmah>
    <errorLog type="Elmah.SqlErrorLog, Elmah"
             connectionStringName="elmah-express" />
    <errorFilter>
      <test>
        <equal binding="HttpStatusCode" value="404" valueType="Int32" />
      </test>
    </errorFilter>
  </elmah>
  <system.web>
    <compilation debug="true" targetFramework="4.0" />
    <httpHandlers>
      <add verb="POST,GET,HEAD" path="elmah.axd"
    type="Elmah.ErrorLogPageFactory, Elmah" />
    </httpHandlers>
    <httpModules>
      <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
    </httpModules>
  </system.web>
</configuration>

And in the code behind throw an error for testing it

throw new Exception("test");

Then on URL type MyPage.axd

Error with log will appear