I'm having the same problem, but in my case, I've just received my board this week.
My version of MCUXpresso is also V10.2.1_795, and the board is the LPCXpresso54608.
On the device manager is showing: LPC-LinkII Ucom Port(COM5).
But when I try to debug, I get the same error as Bill.
Im working with Windows 10.
So I tried to install MCUXpresso on other machine, this time with Windows 7, and it worked fine.
Then I installed everything on another computer, running Windows 10, and I get the same error.
So it seems to be related with Windows version.
What are these "launch configuration files associated with the project" that you mentioned that should be deleted?
Best regards,
Eduardo.