Steps to reproduce:

1. Configure SAML auth with any provider
2. Place the certificates where they belong
3. Edit the IdP certificate by adding any comment to it (example on the screenshot)
4. Try logging in using SAML

Result:
"- Unable to extract public key" error (second screenshot)

Expected:
Successful login because comments beyond the beginning and end of the certificate should be ignored. 

Can cause problems when automating configuration. For example Ansible adds this comment:

# ansible managed. ALL CHANGES WILL BE LOST.