"Self-signed certificate encountered" with Let's Encrypt certificates during installation or curl

Issue

You get the "Self-signed certificate encountered" message with Let's Encrypt certificates during installation or running curl.

Environment

• Imunify360
• ImunifyAV

Solution

The ca-certificates package should be reinstalled. It can be done with the following:

yum reinstall ca-certificates

In some cases, ca-certificates should be removed directly from the rpm database. Before doing this, check if ca-certificates are available via yum:

rpm -e --nodeps --justdb ca-certificates

yum install ca-certificates

Cause

The package `ca-certificates` is outdated.