Certificate signed by unknown authority

We’re experimenting an issue when we try to set a SAML authentication, using Rancher 1.6.

The saml resquest sent by rancher is correcly understood by the IDP.
The SAML response, sent by the IDP, is signed by a self-signed certificate.

On rancher platform, we receive this error message msg=“HandleSamlAssertion failed to Get token from cattle with error Post https://rancher.dev.myxxx.intraxxx.fr/v1/token: x509: certificate signed by unknown authority”.

We imported the self-signed certificate into the /var/lib/rancher/etc/ssl/ directory , but the issue remains.