Create-react-app: ServiceWorker "SecurityError" on Firefox, served from non-standard port

[dandrei]

I have basic CRA app running on a non-standard port (8880, HTTP), some simple functionality, two pages, React Router, Material-UI. It's working great in Chrome and Edge, but on Firefox I get:

Error during service worker registration:

code: 18
columnNumber: 0
data: null
filename: "(...)/js/main.36e5ed39.js"
lineNumber: 1
message: "The operation is insecure."
name: "SecurityError"
result: 2152923154

Is this a known issue having to do with serving from non-standard ports, or do you need more information?

React 16.2.0

[bondz]

Service workers only work when your page is rendered using https. Does your site use https?