Problem:
With the release of Firefox version 140.0 (ESR) and later, MET/TEAM may return a persistent "Unsaved changes" warning.

After this update, users may encounter difficulty closing screens in MET/TEAM (such as the Work Order or Asset screens) even after clicking the Save icon. While the Save function executes correctly and the "Save" button becomes greyed out, clicking the "Close" button triggers the following message:

"Unsaved changes will be lost. Do you want to continue?"

Selecting "Yes" or "No" often fails to close the window, returning the user to the active screen and creating a navigation loop.

Additionally with the ‘Add Result’ button on the Edit Work Order window.  The Work Order will flash but the datasheet doesn’t download.

Issue:
This error is a result of the industry-wide unload event deprecation, which Firefox implemented in version 140 to support the Back-Forward Cache (bfcache) and improve browser performance. By default, Firefox now restricts these listeners, preventing MET/TEAM from correctly signaling to the browser that the data has already been committed to the SQL database.

Temporary Resolution:
To restore the previous behavior in Firefox, the specific deprecation flag must be adjusted in the advanced configuration settings.

1. Open a new tab in Firefox and type about:config in the address bar.

2. Click "Accept the Risk and Continue."

3. In the search box, type: dom.disable_beforeunload

4. Ensure this is set to false. (If it is true, double-click it to toggle).

5. Next, search for: docshell.shorthand_bfcache

6. Set this value to false. This disables the aggressive caching that often suppresses the unload signals required by the current MET/TEAM version.

7. Restart Firefox and log back into MET/TEAM.