The doc talks about a limit of 4 custom domains with certificates here: https://console.bluemix.net/docs/manageapps/secapps.html#ssl_certificate
That same doc used to say something like "If you need more than 4, contact Bluemix to get more for a fee"; can't recall the exact words... that history is not in git. And that confused everyone, including me, as I'd work such a support ticket if it was opened (there was no process for this, or way to do this, which is why it got removed).
The limit of 1 for a Trial account and 4 for a paid account is managed ONLY by the Bluemix UI. The BX CLI does not enforce such limits. I've created 5 custom domains with certs in both a Trial account and a Paid account (see attachments).
I don't understand why there is an arbitrary limit; suggest removing it or making it large enough to accommodate more clients with reasonable needs (e.g. - allow for 10 or more as the limit).
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