If you change the action for that content type to "Always ask" can you select Skype for Business in the popup list and, if you do, does it work?

Hi, yes I have tried. I can see Skype for Business and can select it ,the change is visible and applied in the hadnlers.json file as well. But still nothing happens. Skype is just not starting.

Maybe check for UAC permission issues.

• https://support.mozilla.org/en-US/kb/windows-administrator-launcher-process-error-fix

Hi, I've checked it , but this could not help me. When I set the option for Lync15 to always ask , I see the following notes in the the event viewer :

Application popup: lync.exe - Entry Point Not Found : The procedure entry point GetCurrentProcessId could not be located in the dynamic link library C:\PROGRA~2\MICROS~2\Office16\RtmMvrSplitter.dll.

There was similar issue for Firefox long time, but it was fixed after version 62 or 63.

I don't use Skype for Business, but I guess it is installed as part of Office and hasn't been completely replaced by Teams.

My Registry has this under HKEY_CLASSES_ROOT\lync15\shell\open\command

C:\Program Files (x86)\Microsoft Office\Root\Office16\lync.exe "%1"

which is somewhat different from your path.

After testing a link (and getting a popup to sign in), my handlers.json just shows "4" and the Settings page has "Use Skype for Business (default)" -- there is no path specified in the file.

Could you double-check whether you have that "(default)" option in case the path in your handlers.json is obsolete?

Hi, it has been already tested with value 4 , "Use Skype for Business (default) in the handlers.json file ( with or without path to lync.exe) and is still not working.