When I encountered QuickBooks Error 15215, I got in touch with an expert on call and they suggested me to register some Dynamic Link Library (.DLL) files this way -
Press the Windows key + R to trigger the Run window.
In the search bar, paste - “regsvr32 /s %SystemRoot%\system32\softpub.dll” and “regsvr32 /s %SystemRoot%\system32\WinTrust.dll” one by one, and hit the OK button.
If this does not trigger any error , the file was registered without any issues.
However, if you an error popping up, there is an issue to be checked in your system.
Check if you are using the correct path to register the file.
If there is no error, everything is good to go. Or else, you must escalate this issue to your system administrator or get in touch with the Microsoft team.
You can also have a word with the team to cure QuickBooks Error 15215 on call. Dial 1-855-856-0042.