Www before site name not accepted

[mowebius]

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is: tiimster.com

I ran this command: type www.tiimster.com in browser’s address bar

It produced this output: Security error

My web server is (include version): VPS by OVH

The operating system my web server runs on is (include version): Debian 9

My hosting provider, if applicable, is: OVH

I can login to a root shell on my machine (yes or no, or I don’t know): yes

I’m using a control panel to manage my site (no, or provide the name and version of the control panel): no

Hello, I installed on my VPS site (tiimster.com) a lestencrypt sslcertificate. Everything works fine if I type “tiimster.com” in the browser’s address bar but I get a security alert if I type “www.tiimster.com”:
Message: This connection is not private. This website tries to pretend to be “www.tiimster.com” in order to recover your personal or banking information … (traduction from french)

[jmorahan]

You have a certificate that’s valid for tiimster.com but not www.tiimster.com. To get a certificate that’s valid for both names, you need to specify both names when requesting the certificate. If you don’t know how to do that, please tell us how you obtained the certificate so that we can help you figure it out.

[danb35]

@mowebius

tiimster.com

When you got your certificate, it only covered tiimster.com, not www.tiimster.com. If you want both hostnames to be covered, you'll need to reissue the cert with both of them.