Native Add-on not installed message

[wisemonkey]

Addon and native addons are installed correctly.
I can see

➜  native-messaging-hosts pwd
/home/wisemonkey/.mozilla/native-messaging-hosts

➜  native-messaging-hosts ls
firefox-webserial  io.github.kuba2k2.webserial.json

➜  native-messaging-hosts cat io.github.kuba2k2.webserial.json 
{
	"name": "io.github.kuba2k2.webserial",
	"description": "WebSerial for Firefox",
	"path": "/home/wisemonkey/.mozilla/native-messaging-hosts/firefox-webserial",
	"type": "stdio",
	"allowed_extensions": ["webserial@kuba2k2.github.io"]
}

Opening any webserial site says `native add-on not installed`
and debug console shows:
19:31:09.650 / NATIVE -- getNativePort: Connecting to native... [webserial.background.js:1:20764](moz-extension://bdca7b20-f765-4826-87cc-0940a94f90cc/dist/webserial.background.js)
19:31:09.651 / NATIVE -- setNativeParams: 
Object { state: "checking", platform: {…} }
[webserial.background.js:1:20764](moz-extension://bdca7b20-f765-4826-87cc-0940a94f90cc/dist/webserial.background.js)
19:31:09.659 / NATIVE -- onDisconnect: Disconnected: Error: No such native application io.github.kuba2k2.webserial [webserial.background.js:1:20764](moz-extension://bdca7b20-f765-4826-87cc-0940a94f90cc/dist/webserial.background.js)
19:31:09.659 / NATIVE -- setNativeParams: 
Object { state: "not-installed", error: Error, platform: {…} }
[webserial.background.js:1:20764](moz-extension://bdca7b20-f765-4826-87cc-0940a94f90cc/dist/webserial.background.js)

Is it not installed / connected correctly

I can do:

➜  native-messaging-hosts ./firefox-webserial 
0{"data":"Waiting for incoming connections...\n"}^C

[wisemonkey]

I installed ungoogled-chromium and that worked.
However I had to do sudo setfacl -m u:USERNAME:rw /dev/ttyUSB0 - maybe something similar is needed?

[kuba2k2]

Not really. Your Firefox can't see the native application. Why - that's not something I could know. Maybe check permissions for the folders and files you've created for the native application.

[wisemonkey]

Not really. Your Firefox can't see the native application. Why - that's not something I could know. Maybe check permissions for the folders and files you've created for the native application.

I installed with script (also tried manual installation later) - permissions seem ok

➜  native-messaging-hosts ls -l                  
total 156
-rwxr-xr-x. 1 wisemonkey wisemonkey 154280 Sep 20 12:18 firefox-webserial
-rw-r--r--. 1 wisemonkey wisemonkey    237 Sep 20 10:09 io.github.kuba2k2.webserial.json

[N0tACyb0rg]

If you've installed Firefox as a Flatpak, you need to add the native-messaging-hosts path to the list of directories that Firefox can see, either through directly overriding it or through Flatseal.