Some QuickBooks Desktop users may be prompted with a message “Application cannot be started. Contact the application vendor.”
Solution 1 - Rename Windows local/apps/2.0 folder
Completely shut down the Sync Engine.
In Windows, navigate to the folder:
c:\users\[username]\appdata\local\apps\2.0
Where [username] is the name of the Windows user (as shown in the image below):
However, this folder is generally hidden by default, you can unhide that folder by going to:
Organize > Folder and Search Option.
Click on View tab.
Click on Show Hidden files, folder and drives.
Rename the
2.0folder (choose a name that makes sense for you).Run the Method Sync Engine. This will recreate the folder you renamed above.
At this point, the sync engine should run properly.
Solution 2 - Disable / Re-enable antivirus
If Solution 1 does not work for you, your antivirus program may be conflicting with the sync engine.
Disable your antivirus program.
Turn off the Windows Defender Firewall:
Control Panel ⇨
System & Security ⇨
Windows Defender Firewall ⇨
Turn Windows Defender Firewall off.
Re-enable your antivirus program and the Windows Defender Firewall.
At this point, the sync engine should run properly.