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CO-piBOT: return = 21

This code indicates the certificate found on the server has not been recognized by our test tool.

  • If this certificate has been delivered by TBS INTERNET, it has been wrongly installed. In most cases it comes from the certification chain that is not or wrongly displayed.
    See our installation instructions (in the delivery e-mail) and make sure the chain has been properly installed (voir Install a server certificate, look at the B file for an Apache installation or for Microsoft Install intermediate certificates or root certificates manually).

  • This message can also be sparked off if you bought a certificate issued by a certification authority we do not trust and with we chose not to work.

Error messages that client browsers might display

This may result in the following error message:

Microsoft Internet Explorer

There is a problem with this website's security certificate.

The security certificate presented by this website was issued for a different website's address.

Security certificate problems may indicate an attempt to trick or intercept the data you send to the server.

We recommend that you close this webpage and do not continue to this website.

Click here to close this webpage
Continue to this website (not recommended)
More informations

Google Chrome

This is probably not the site you are looking for!

You attempted to reach example.domain.combut, instead, you are currently communicating with a server identified as * This may be due to a server misconfiguration or something more serious. A hacker on your network may be trying to make you visit a fake version of You should not proceed, especially if you have never seen this warning before for this site.

Apple Safari, Apple Mail, Iphone, IPad, ...

Safari can't verify the identity of the website <<>>

The certificate for this website is invalid. You might be connecting to a website that is pretending to be <<>>, which could put your confidential information at risk. Would you like to connect to the website anyway?

Mozilla Firefox, Thunderbird, ...

This Connection is Untrusted

You have asked Firefox to connect securely to, but we can't confirm that your connection is secure.

Normally, when you try to log in securely, sites present a certified ID to prove that you are at the correct address. However, the identity of the site cannot be verified.

What should I do?

If you usually log in to this site without problems, this error may mean that someone is trying to impersonate this site and you should not proceed.

Technical details

Web sites use certificates to prove their identity. Firefox doesn't trust this site because it uses an invalid certificate for
The certificate is only valid for the following names: