Please check the following list of potential issues if you're getting security errors when setting up your custom domain.

You can access your custom domain settings in Mobilize under yourcommunity.mobilize.io/main/settings/general --> Edit your domain.

CNAME Record

The CNAME value should be yourregulardomain.custom-domain.mobilize.io. For example, if your brand is called ABC and your website is abc.com, then your CNAME value should be abc.custom-domain.mobilize.io.

SSL Checker

If you get an SSL error on some devices but not on Chrome, you may need to add your intermediate certificates. You can make sure your custom-domain settings work using this utility.

RSA Format

Your private key should NOT be password protected. If it is remove the password with openssl rsa -in server.pass.key -out server.key
Your private key is in RSA format. You can verify that by making sure server.key starts with -----BEGIN RSA PRIVATE KEY----- and NOT -----BEGIN PRIVATE KEY-----

Trying to run

openssl rsa -in server.pass.key -out server.key

If your formatting isn't correct, paste the CRT (NOT the chain/bundle) in the SSL box along with the key.

Ensure the key matches the certificate

To verify that an RSA private key matches the RSA public key in a certificate you need to

Verify the consistency of the private key.
Compare the modulus of the public key in the certificate against the modulus of the private key.

To verify the consistency of the RSA private key and to view its modulus:
openssl rsa -modulus -noout -in myserver.key | openssl md5

To view the modulus of the RSA public key in a certificate:
openssl x509 -modulus -noout -in myserver.crt | openssl md5

Setup Guide

The complete setup article is at http://help.mobilize.io/advanced-features-and-integrations/setting-up-a-custom-domain