Opening web link fails

What I’m trying to do

Open links in Obsidian

Things I have tried

I’m not sure what to try here, although I did test that running firefox <url> in my terminal works perfectly fine.

Here is the pop-up window I get from Obsidian:

Perhaps including the text in the post is good for googleability: Firefox is already running, but is not responding. To use Firefox, you must first close the existing Firefox process, restart your device, or use a different profile.