We purchased an SSL certificate through DNSimple and installed it on our Heroku SSL endpoint. Now navigating to the app via SSL works fine on Chrome and Safari, but Firefox shows a "This connection is untrusted" error. Why would an SSL cert be untrusted by Firefox only?
We figured out the problem:
The Heroku docs point to the following bundle.pem file, which DOES NOT WORK FOR FIREFOX: https://knowledge.rapidssl.com/library/VERISIGN/ALL_OTHER/RapidSSL%20Intermediate/RapidSSL_CA_bundle.pem
The CORRECT bundle.pem file is at:
https://knowledge.rapidssl.com/library/VERISIGN/INTERNATIONAL_AFFILIATES/RapidSSL/AR1548/RapidSSLCABundle.txt
as indicated on the RapidSSL site.
Heroku docs need to be updated. Hopefully this saves someone else some time..
UPDATE: We reported this to Heroku and they updated their docs, so this is no longer an issue.