Your connection is not private err_cert_authority_invalid

Fixed the bug. Your connection is not private err_cert_authority_invalid? We can help you.

With this error, sites secured with Let’s Encrypt Certificates display ERR_CERT_AUTHORITY_INVALID warning after September 30, 2021.

As part of our Server Management Services, we assist our customers with several Plesk queries.

Today, let’s see how we can correct this mistake.

Your connection is not private err_cert_authority_invalid

Most often, the symptom of this error is as follows:

  • After September 30, 2021, sites hosted and secured on a Plesk with Let’s Encrypt certificates will show the ERR_CERT_AUTHORITY_INVALID error.
  • We see the DST Root CA X3 certificate in the certificate chain (Padlock icon in the address bar> Certificate> Certification Path).

Generally, the cause of this error is the expiration of the DST Root CA X3 root certificate on September 30, 2021 at. 14:01:15 GMT.

This can affect outdated client operating systems, including:

  1. Windows
  2. Windows 7
  3. macOS <10.12.1
  4. iOS <10
  5. Android <7.1.1
  6. Ubuntu <16.04
  7. Debian <8

Let’s see how our support technicians fix this error.

Once in Windows Server, we install the latest OS updates and restart the server to update the root certificate cache.

On the other hand, for an outdated Linux server, we need to apply the following steps:

  1. Initially, we connect to the server using SSH.
  2. Then we open the file /etc/ca-certificates.conf for editing.
  3. Finally, we comment on the line mozilla / DST_Root_CA_X3.crt by putting the symbol,! to the beginning of the line and save the file.
  4. Finally, we execute the command:
    # update-ca-certificate

In the event that we receive TLS errors in the contact form or email clients, we change the host name to the server’s host name instead of the mail.domain name.

[Need help with the fix? We are here for you]


In short, we saw how our support technicians solve the Plesk error for our customers.


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