With @Michel_Edward 's generous patient assistance, we managed to find and solve the problem.
The UI for managing the protocol handlers in Firefox is a little broken. You can fix it by telling Firefox to use the system default handler “net-steinberg-sda://
” URLs by finding this section in the handlers.json
file and ensuring it looks like this:
{
...
"schemes": {
...
"net-steinberg-sda": {
"action": 4
}
}
}
Deleting the file and allowing Firefox to recreate it will also work, but you’ll lose any other protocols that have been registered - which could be annoying.
If it’s a common problem, I might consider writing a little script to fix that file programmatically.