It would be good to mention here that you need to remove any newlines or spaces in the certificate before you paste it into the field. As typically PEM formatted certificate files split into multiple lines.

[Darren] This possibly refer to the content here regarding PEM formatted certificates.

Reported by: jmetso

https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.13/html/administering_the_api_gateway/apicast-policies#annotations:6f51a460-b689-4258-93a3-212671c1a17f