How to Fix: Firefox Refuses IIS Express Certificate with error "SEC_ERROR_INADEQUATE_KEY_USAGE"
IIS Express Certificate Error SEC_ERROR_INADEQUATE_KEY_USAGE
📋 Table of Contents
Firefox Refuses IIS Express Certificate with error 'SEC_ERROR_INADEQUATE_KEY_USAGE': This issue affects users who are trying to connect to a web application hosted on IIS Express using Firefox, but not Chrome. The error message indicates that the certificate key usage is inadequate for the attempted operation, preventing Firefox from establishing a secure connection.
This error can be frustrating as it prevents users from accessing their web applications, and there seems to be no way to accept or continue with the certificate installation. However, by following the steps outlined in this guide, you should be able to resolve the issue and regain access to your web application.
⚠️ Common Causes
- The primary reason for this error is that IIS Express is using a certificate with key usage that is not compatible with Firefox's expectations. This can happen when the certificate is generated or imported incorrectly, or if there are issues with the certificate chain or trust anchors.
- An alternative cause could be that the certificate is being used in an invalid context. For example, if the certificate is being used for both HTTP and HTTPS connections without proper configuration, it may lead to this error.
🔧 Proven Troubleshooting Steps
Regenerating Firefox's Certificate Store
- Step 1: Delete the existing Firefox certificate store files, specifically cert9.db and cert8.db. You can do this by navigating to the following folder and deleting the files: C:\Users\YourUsername\AppData\Roaming\Mozilla\Firefox\Profiles\
- Step 2: Restart Firefox after deleting the certificate store files.
- Step 3: After restarting, try accessing your web application again to see if the error persists.
Configuring IIS Express Certificate Options
- Step 1: Open the IIS Express configuration file (usually located in C:\Program Files\IIS Express\config\appcmd.config) and add the following line under the
section: NonRepudiation - Step 2: Save the changes to the configuration file and restart IIS Express.
- Step 3: After restarting, try accessing your web application again to see if the error persists.
🎯 Final Words
To summarize, the 'SEC_ERROR_INADEQUATE_KEY_USAGE' error in Firefox can be resolved by regenerating Firefox's certificate store or configuring IIS Express certificate options. By following these steps, you should be able to regain access to your web application and resolve this issue.
❓ Frequently Asked Questions
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