I had been using JFK, LAX, and DFW FSDT for sometime without issues. Last time I appeared to have used LAX was in February (shockingly)
The old Addon Manager might have worked and, if nothing happened in your system that would eventually triggered a reactivation (a Windows reinstall, a bios update, a major change of an hardware component ), you could foreseeably stay with the previous version "forever".
The problems would start if you had to reactivate for any of these reasons: THEN you MUST had the updated Addon Manager, since the Esellerate servers closed in 2019, so there would be nobody the old software could talk to, that's why you need the updated software, otherwise there would be no way to exit from Trial.
Since the new software is confirmed to work in Windows 10, I already listed all the the only possible reasons why it might not work for you, with all the known possible solutions:
- The Addon Manager MUST be installed last. If you reinstall any scenery for FS9, you MUST reinstall the Addon Manager again, because the installer might "downgrade" it to the Esellerate version, since we have updated the Stand-Alone Addon Manager for FS9, but not the single products installers, that's why the last thing you do must be installing the Stand-Alone Addon Manager for FS9.
- The antivirus might interfere, blocking the update or, even worse, blocking some files and let pass others, which will 100% result in a crash on start. This should be fixed by adding the WHOLE FS9 FOLDER to the antivirus Exclusions then THEN reinstall the Stand-Alone Addon Manager for FS9 again, to be sure the correct version is installed fully without antivirus interference
- You might miss some .NET libraries required by the new software to work. This shouldn't normally happen, since the Addon Manager installer will surely install them in FS9 and register them in Windows. That's why I said to try the new Uninversal Installer which, although the program itself is not used for FS9, it will install and register the same libraries, so maybe it would work, but that's not normally required.
You might try this last thing:
- Go in the Windows Control Panel, and UNINSTALL the Addon Manager for FS9 AND (important) reply YES to the question "Do you want to the remove the Addon Manager?"
- After the uninstall is complete, reinstall it again, maybe the previous uninstall manager to clean up some leftover files that needed to be removed.