What is Elmah

According to Scott Mitchell, Error Logging Modules And Handlers (ELMAH) offers another approach to log runtime errors in a production environment. ELMAH is a free, open source error logging library that includes features like error filtering and the ability to view the error log from a web page, as an RSS feed, or to download it as a comma-delimited file.

What we will achieve through Elmah

Step 1: Create a MVC web Application

Open Visual Studio create new project or press CTRL +SHIFT +N. Go to Web tab, select ASP.NET Web Application template. Give name as MVCExceptionLog as in the following screenshot,



Step 2: Add Elmah Package from Nuget,

Right click on project solution go to Manage NuGetPackages for Solution, click on it and search elmah and install it,

Step 3: Now open web config file and add the following code inside <system.web> </system.web>,

  1. <!--add this-->
  2. < httpHandlers >
  3. < add verb = "POST,GET,HEAD"path = "elmah.axd"type = "Elmah.ErrorLogPageFactory, Elmah" / >
  4. < /httpHandlers>
  5. <!--add this-->

Also, add the following code inside <system.webServer></system.webServer>,

  1. <!--add this-->
  2. < handlers >
  3. < add name = "Elmah"verb = "POST,GET,HEAD"path = "elmah.axd"type = "Elmah.ErrorLogPageFactory, Elmah" / >
  4. < /handlers>
  5. <!--add this-->

Step 4: Create table and Stored Procedure,

Here I am using SQL Server database to log the exception. I have already created database SQL Server named ExceptionLog. Open SQL Server Management Studio, run the following code in ExceptionLog database one by one.

For Table

  1. CREATE TABLE[dbo].[ELMAH_Error]
  2. (
  4. [ErrorId][uniqueidentifier] NOT NULL,
  6. [Application][nvarchar](60) NOT NULL,
  8. [Host][nvarchar](50) NOT NULL,
  10. [Type][nvarchar](100) NOT NULL,
  12. [Source][nvarchar](60) NOT NULL,
  14. [Message][nvarchar](500) NOT NULL,
  16. [User][nvarchar](50) NOT NULL,
  18. [StatusCode][int] NOT NULL,
  20. [TimeUtc][datetime] NOT NULL,
  22. [Sequence][int] IDENTITY(1, 1) NOT NULL,
  24. [AllXml][ntext] NOT NULL
  26. )

Stored procedure

    1. Create PROCEDURE[dbo].[ELMAH_GetErrorsXml]
    3. (
    4. @Application NVARCHAR(60),
    5. @PageIndex INT = 0,
    6. @PageSize INT = 15,
    7. @TotalCount INT OUTPUT
    9. )
    11. AS
    13. SET NOCOUNT ON
    15. DECLARE @FirstTimeUTC DATETIME
    16. DECLARE @FirstSequence INT
    17. DECLARE @StartRow INT
    18. DECLARE @StartRowIndex INT
    19. SELECT
    21. @TotalCount = COUNT(1)
    23. FROM
    25. [ELMAH_Error]
    27. WHERE
    29. [Application] = @Application
    30. SET @StartRowIndex = @PageIndex * @PageSize + 1
    31. IF @StartRowIndex <= @TotalCount
    33. BEGIN
    35. SET ROWCOUNT @StartRowIndex
    37. SELECT
    39. @FirstTimeUTC = [TimeUtc],
    41. @FirstSequence = [Sequence]
    43. FROM
    45. [ELMAH_Error]
    47. WHERE
    49. [Application] = @Application
    51. ORDER BY
    53. [TimeUtc] DESC,
    54. [Sequence] DESC
    56. END
    58. ELSE
    60. BEGIN
    62. SET @PageSize = 0
    64. END
    66. SET ROWCOUNT @PageSize
    68. SELECT
    70. errorId = [ErrorId],
    72. application = [Application],
    73. host = [Host],
    74. type = [Type],
    75. source = [Source],
    76. message = [Message],
    77. [user] = [User],
    78. statusCode = [StatusCode],
    79. time = CONVERT(VARCHAR(50), [TimeUtc], 126) + 'Z'
    81. FROM
    83. [ELMAH_Error] error
    85. WHERE
    87. [Application] = @Application
    89. AND
    91. [TimeUtc] <= @FirstTimeUTC
    93. AND
    95. [Sequence] <= @FirstSequence
    97. ORDER BY
    99. [TimeUtc] DESC,
    101. [Sequence] DESC
    103. FOR
    105. XML AUTO

    1. Create PROCEDURE[dbo].[ELMAH_GetErrorXml]
    3. (
    5. @Application NVARCHAR(60),
    6. @ErrorId UNIQUEIDENTIFIER
    8. )
    10. AS
    12. SET NOCOUNT ON
    13. SELECT
    15. [AllXml]
    16. FROM
    18. [ELMAH_Error]
    19. WHERE
    21. [ErrorId] = @ErrorId
    22. AND
    23. [Application] = @Application

    1. Create PROCEDURE[dbo].[ELMAH_LogError]
    3. (
    5. @ErrorId UNIQUEIDENTIFIER,
    6. @Application NVARCHAR(60),
    7. @Host NVARCHAR(30),
    8. @Type NVARCHAR(100),
    9. @Source NVARCHAR(60),
    10. @Message NVARCHAR(500),
    11. @User NVARCHAR(50),
    12. @AllXml NTEXT,
    13. @StatusCode INT,
    14. @TimeUtc DATETIME
    16. )
    18. AS
    20. SET NOCOUNT ON
    22. INSERT
    24. INTO
    26. [ELMAH_Error]
    27. (
    29. [ErrorId],
    30. [Application],
    31. [Host],
    32. [Type],
    33. [Source],
    34. [Message],
    35. [User],
    36. [AllXml],
    37. [StatusCode],
    38. [TimeUtc]
    40. )
    42. VALUES
    44. (
    46. @ErrorId,
    47. @Application,
    48. @Host,
    49. @Type,
    50. @Source,
    51. @Message,
    52. @User,
    53. @AllXml,
    54. @StatusCode,
    55. @TimeUtc
    57. )

After creating the database table and stored procedure. The schema will look like the following:


Now again open web config file, add the following code inside in <configuration>,
  1. </configuration>
  2. <elmah>
  3. <!--. If allowRemoteAccess value is set to 0, then the error log web page can only be viewed locally. If allowRemoteAccess attribute is set to 1 then the error log web page is enabled for both remote and local visitors.-->
  4. <!--add this-->
  5. <security allowRemoteAccess="0" />
  6. <!-- DefaultConnection is the name of database connection string -->
  7. <errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="DefaultConnection" />
  8. <!--add this-->
  9. </elmah>
Now my final webconfig file look like the following,
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <!--
  3. For more information on how to configure your ASP.NET application, please visit
  4. http://go.microsoft.com/fwlink/?LinkId=301880
  5. -->
  6. <configuration>
  7. <configSections>
  8. <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
  9. <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  10. <sectionGroup name="elmah">
  11. <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
  12. <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah" />
  13. <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
  14. <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
  15. </sectionGroup>
  16. </configSections>
  17. <connectionStrings>
  18. <add name="DefaultConnection" connectionString="Data Source=.;Initial Catalog=ExceptionLog;Integrated Security=True" providerName="System.Data.SqlClient" />
  19. </connectionStrings>
  20. <appSettings>
  21. <add key="webpages:Version" value="3.0.0.0" />
  22. <add key="webpages:Enabled" value="false" />
  23. <add key="ClientValidationEnabled" value="true" />
  24. <add key="UnobtrusiveJavaScriptEnabled" value="true" />
  25. <add key="elmah.mvc.disableHandler" value="false" />
  26. <add key="elmah.mvc.disableHandleErrorFilter" value="false" />
  27. <add key="elmah.mvc.requiresAuthentication" value="false" />
  28. <add key="elmah.mvc.IgnoreDefaultRoute" value="false" />
  29. <add key="elmah.mvc.allowedRoles" value="*" />
  30. <add key="elmah.mvc.allowedUsers" value="*" />
  31. <add key="elmah.mvc.route" value="elmah" />
  32. <add key="elmah.mvc.UserAuthCaseSensitive" value="true" />
  33. </appSettings>
  34. <system.web>
  35. <authentication mode="None" />
  36. <compilation debug="true" targetFramework="4.5.1" />
  37. <httpRuntime targetFramework="4.5.1" />
  39. <!--add this-->
  40. <httpHandlers>
  41. <add verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
  42. </httpHandlers>
  44. <!--add this-->
  45. <httpModules>
  46. <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
  47. <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" />
  48. <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" />
  49. </httpModules>
  50. </system.web>
  51. <system.webServer>
  52. <!--add this-->
  53. <handlers>
  54. <add name="Elmah" verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
  55. </handlers>
  56. <!--add this-->
  57. <modules>
  58. <remove name="FormsAuthentication" />
  59. <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" preCondition="managedHandler" />
  60. <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" preCondition="managedHandler" />
  61. <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" preCondition="managedHandler" />
  62. </modules>
  63. <validation validateIntegratedModeConfiguration="false" />
  65. </system.webServer>
  66. <runtime>
  67. <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  68. <dependentAssembly>
  69. <assemblyIdentity name="Microsoft.Owin" publicKeyToken="31bf3856ad364e35" />
  70. <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  71. </dependentAssembly>
  72. <dependentAssembly>
  73. <assemblyIdentity name="Microsoft.Owin.Security.OAuth" publicKeyToken="31bf3856ad364e35" />
  74. <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  75. </dependentAssembly>
  76. <dependentAssembly>
  77. <assemblyIdentity name="Microsoft.Owin.Security.Cookies" publicKeyToken="31bf3856ad364e35" />
  78. <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  79. </dependentAssembly>
  80. <dependentAssembly>
  81. <assemblyIdentity name="Microsoft.Owin.Security" publicKeyToken="31bf3856ad364e35" />
  82. <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  83. </dependentAssembly>
  84. <dependentAssembly>
  85. <assemblyIdentity name="Newtonsoft.Json" culture="neutral" publicKeyToken="30ad4fe6b2a6aeed" />
  86. <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
  87. </dependentAssembly>
  88. <dependentAssembly>
  89. <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
  90. <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  91. </dependentAssembly>
  92. <dependentAssembly>
  93. <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
  94. <bindingRedirect oldVersion="0.0.0.0-5.2.2.0" newVersion="5.2.2.0" />
  95. </dependentAssembly>
  96. <dependentAssembly>
  97. <assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35" />
  98. <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />
  99. </dependentAssembly>
  100. <dependentAssembly>
  101. <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
  102. <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
  103. </dependentAssembly>
  104. <dependentAssembly>
  105. <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
  106. <bindingRedirect oldVersion="0.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" />
  107. </dependentAssembly>
  108. </assemblyBinding>
  109. </runtime>
  110. <entityFramework>
  111. <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
  112. <parameters>
  113. <parameter value="mssqllocaldb" />
  114. </parameters>
  115. </defaultConnectionFactory>
  116. <providers>
  117. <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
  118. </providers>
  119. </entityFramework>
  120. <elmah>
  122. <!--add this-->
  123. <!--. If allowRemoteAccess value is set to 0, then the error log web page can only be viewed locally. If this attribute is set to 1 then the error log web page is enabled for both remote and local visitors.-->
  124. <security allowRemoteAccess="0" />
  125. <errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="DefaultConnection" />
  126. <!--add this-->
  127. </elmah>
  129. </configuration>
Step 5: Let us create some exception
  1. Suppose I want to open a page that are not in our application. Let us say About2 page: localhost:55776/Home/About2
  2. Create divide by zero exception in contact page
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Web;
  5. using System.Web.Mvc;
  6. namespace MVCExceptionLog.Controllers
  7. {
  8. public class HomeController: Controller
  9. {
  10. public ActionResult Index()
  11. {
  12. return View();
  13. }
  14. public ActionResult About()
  15. {
  16. ViewBag.Message = "Your application description page.";
  17. return View();
  18. }
  19. public ActionResult Contact()
  20. {
  21. int a = 0;
  22. int b;
  23. b = 1 / a;
  24. ViewBag.Message = "Your contact page.";
  25. return View();
  26. }
  27. }
  28. }

Step 5: Run the application,

Click on F5 and register a user.


Step 6: View the Error Log from a Web Page,

You can view the error log web page through the url localhost:portno/elmah.axd like, localhost:55776/elmah.axd.

Check the error log in database.
Point of Interest

In this article we learned how to log Exception in SQL Server and view error log details from web page.