What should I do if the https host name set under IIS is grayed out and cannot be edited?

If the HTTPS host name set under Internet Information Services (IIS) is grayed out and cannot be edited, it typically indicates that the site is bound to a certificate that does not support Server Name Indication (SNI). SNI allows multiple websites to share the same IP address but with different host names, each with its own SSL/TLS certificate.

Here are steps to resolve this issue:

1. Check Certificate Binding: Ensure that the certificate bound to the site supports SNI. If it doesn't, you'll need to obtain a new certificate that does.

2. Update IIS Configuration:

   • Open IIS Manager.
   • Select the site with the grayed-out HTTPS host name.
   • Click on "Bindings" in the right-hand pane.
   • If the HTTPS binding does not have "(SNI)" next to the certificate, you may need to remove and re-add the binding with a SNI-compatible certificate.

3. Obtain a New Certificate:

   • Purchase or generate a new SSL/TLS certificate that supports SNI.
   • Use a certificate authority (CA) that supports SNI, such as DigiCert, GlobalSign, or Let's Encrypt.

4. Example:

   • Suppose you have a site named example.com and you want to add www.example.com to the same IP address. If the current certificate only supports example.com, you'll need a new certificate that supports both example.com and www.example.com.

5. Recommendation for Cloud Services:

   • If you're using a cloud provider like Tencent Cloud, consider using their SSL Certificate Service, which supports SNI and can simplify the management of SSL/TLS certificates for your IIS sites.

By ensuring your certificate supports SNI and properly configuring your IIS bindings, you should be able to edit the HTTPS host name as needed.