When you try to access a URL that requires Client Certificate Authentication (https://subdomain name.s.cybozu.com/), you may see the error message "A valid client certificate is required to access this site. Code: 496 No Cert" and be unable to access the URL.

To use Client Certificate Authentication, you must have a client certificate installed in your web browser or on your mobile device.
Check that a client certificate is installed, and then try to access the URL again.
As an example, the steps on this page describe how to check that a client certificate is installed (and how to install a client certificate, if necessary) when using Google Chrome on Windows. The installation steps vary depending on the version of OS or web browser being used.

Follow the steps below to check whether a client certificate for Client Certificate Authentication has been installed in your web browser or on your mobile device.

1. Start Google Chrome.

2. Click the menu icon at the top right of Google Chrome.

3. Click Settings.

4. Click Security under Privacy and security.

5. Click Manage certificates.

6. Click the Personal tab.

7. Check if a client certificate is installed.
   If you find "cybozu.com client certificate" under Friendly Name, it means you have a client certificate installed.

If a client certificate is installed, refer to If a client certificate is installed.
If not, refer to If a client certificate is not installed.

1. Restart Google Chrome.

2. Use Incognito mode to access the URL that requires Client Certificate Authentication ((https://subdomain name.s.cybozu.com/).
   For details, refer to the following page.
   Google Chrome Help: Browse in Incognito mode

If a client certificate is not installed, the steps to take depend on whether you can log in to kintone from either another device or a web browser.

Contact a Users & System Administrator for assistance.

Follow the steps below to install a client certificate.

1. Click the Open the Account Settings icon (the down arrow at the top right of kintone), then click Account Settings.

2. Click Mobile Access and write down the password displayed in the Client Certificate section.

3. Expand Access via Web Browser and enter your e-mail address with which you want to receive a client certificate. 　

4. From the device you want to use, double-click the client certificate that you received ("***.pfx").
   The Certificate Import Wizard will be launched.

5. Select "Current User" as the store location, then click Next.

6. Confirm that the client certificate is displayed in the "File name:" field, then click Next.

7. Enter the password for the client certificate, select Include all extended properties in the Import Options section, and then click Next.

8. Select Automatically select the certificate store based on the type of certificate and click Next.

9. Click Finish.
   

10. Click OK.