Troubleshooting IIS 500.19 Errors: Configuration and Permissions

Understanding and Resolving IIS 500.19 Errors

The "HTTP Error 500.19 – Internal Server Error" in IIS (Internet Information Services) indicates that the server is encountering difficulties accessing or interpreting your website’s configuration file (typically web.config). This error often arises from permission issues or missing components required to process the configuration. This tutorial will guide you through the common causes of this error and how to resolve them.

What Causes a 500.19 Error?

Several factors can lead to a 500.19 error:

• Insufficient Permissions: The account under which your application pool runs (the process that handles your website’s requests) does not have the necessary permissions to read the web.config file or the website’s directory.
• Missing Features: Required IIS features, such as ASP.NET or URL Rewrite modules, may not be installed.
• Configuration Errors: While the error message suggests configuration corruption, it often results from inability to read the configuration due to permissions.
• Incorrect Application Pool Identity: The identity configured for your application pool may be misconfigured or lack the required privileges.

Identifying the Root Cause

Before diving into solutions, let’s pinpoint the problem. The error message provides valuable clues:

• Module: IIS Web Core – This indicates a core IIS issue, typically related to configuration access.
• Error Code: 0x80070005 – This hexadecimal code translates to "Access is denied," reinforcing the possibility of permission issues.
• Config File: The path to your web.config file – confirming which file is causing the problem.

Solutions

Here’s a step-by-step approach to resolving the 500.19 error:

1. Verify and Adjust Permissions

This is the most common solution. You need to ensure the account running your application pool has read access to your website’s directory and, critically, the web.config file.

• Identify the Application Pool Identity: In IIS Manager, navigate to "Application Pools." Locate the application pool associated with your website and examine its "Identity" setting. Common identities include ApplicationPoolIdentity, NetworkService, or a custom account.
• Grant Permissions:
  1. In Windows Explorer, navigate to the directory containing your web.config file.
  2. Right-click on the web.config file and select "Properties."
  3. Go to the "Security" tab.
  4. Click "Edit" to change permissions.
  5. Add the identity account identified in step 1.
  6. Grant at least "Read & Execute" permissions. Avoid granting "Write" permissions unless your application specifically requires them.
  7. Repeat the process for the website’s root directory to ensure the identity has access to all necessary files.
• Consider the IIS_IUSRS Group: In some configurations, adding the IIS_IUSRS group to the permissions list can also resolve the issue. This group represents anonymous users, and while granting full permissions isn’t usually recommended, it can be a quick fix for testing purposes.

2. Ensure Required IIS Features are Installed

Your website may rely on specific IIS features. If these are missing, the server won’t be able to process the configuration correctly.

• Open "Turn Windows features on or off." (Search for it in the Windows search bar.)
• Expand "Internet Information Services."
• Expand "World Wide Web Services."
• Expand "Application Development Features."
• Make sure "ASP.NET" is checked. If your application uses a specific version of ASP.NET, ensure that version is selected.
• If you’re using URL Rewrite, ensure the "URL Rewrite" feature is checked.
• Click "OK" and restart IIS (by restarting the server or using IIS Manager).

3. Check Application Pool Identity

The Application Pool Identity dictates the account under which your website runs. Using ApplicationPoolIdentity is generally recommended for security reasons, as it creates a unique identity for your application.

• In IIS Manager, navigate to "Application Pools."
• Right-click on the application pool associated with your website and select "Advanced Settings."
• Under "Process Model," verify the "Identity" setting. If it’s not ApplicationPoolIdentity, consider changing it to improve security and potentially resolve the error. Restart the application pool after making changes.

4. Troubleshooting Further

• Clear IIS Express Cache (if applicable): If you’re using IIS Express for development, clearing its cache can sometimes resolve configuration issues.
• Review Event Logs: The Windows Event Viewer may contain more detailed error messages that can help pinpoint the root cause. Look for errors related to IIS or your application.
• Simplify Configuration: Temporarily simplify your web.config file by removing non-essential configurations to see if the error resolves. If it does, gradually add back configurations to identify the problematic setting.