Hello Mohamed

Could you explain better what you are debugging?
Is it O11 or ODC? Are you debugging server-side or client-side?

As far as I know (unless there is something new that I didn't see), client-side debugging is possible only on Chrome/Edge, not on Firefox.

Server-side debugging "should" work if the interface is loaded in any browser (I've never really tested it).

Cheers!

EDIT:

If you are debugging server-side, this may happen if we add breakpoints to code that we forgot to publish, or if someone else published the module/app, making changes to the same code, and we didn't reload the module/app in the studio.

EDIT 2:
Tested it and server-side debugging works on Firefox.

Hello.

OutSystems debugger was built for Chrome as you can read in the documentation. I think it connects with Chrome DevTools Protocol, but never explored that topic.

https://success.outsystems.com/documentation/11/debugging_apps/

Edge is also a Chromium-based browser so it should work, but Chrome is the sure option.

https://success.outsystems.com/documentation/11/setup_outsystems_infrastructure_and_platform/setting_up_outsystems/outsystems_11_system_requirements

Try this:

• Console for JavaScript errors
• Debugger add breakpoints to JavaScript loaded by the page.
• Network inspect requests, responses, payloads and failed calls.
• Inspector analyse the generated HTML and CSS.

Enable Persist Logs in the Network tab if the issue happens during navigation or page refresh. OutSystems also documents Firefox DevTools as a valid way to capture network/HAR information. 

In OutSystems the only thing you can debug is the server side requests.