Program that starts a Popper emulator's games missing
What it means
No game of this emulator starts from Popper.
Why it happens
The launch script names the program that starts the game with its place under the emulator's launch folder ([DIREMU]), for example FPLoader.exe for Future Pinball, or steam.exe. That launch folder is stored in PinUP Popper's database: it often still names where the program was on another PC, or before it was moved or reinstalled.
How Pincab Toolbox detects it
The emulator is visible, has at least one visible game, and its launch folder exists; its script has one single line outside comments shaped START "" "[DIREMU]\program.exe" that carries the game ([GAMEFULLNAME] or [GAMENAME]), no line that could skip it (if, for, goto, call, else, exit, a parenthesis), and that program does not exist at that place. Other shape read: a line cd "[DIREMU]" followed, on the next command, by START "" "program.exe" that carries the game; the program is then reported missing when it is neither in the launch folder, nor in Popper's folder, nor in the PATH. A line if "…"=="…" (SET …) written on a single line does not count as able to skip the launch.
Check your own pincab
Pincab Toolbox is a free Windows scanner for Visual Pinball X and PinUP Popper. It finds and explains problems like this one. No account, no telemetry.
Download for freeCovered: Visual Pinball X (10.x) and PinUP Popper. Partly covered, read only: PinballX and PinballY (their settings and game lists). Not covered: Future Pinball, Pinball FX, Visual Pinball 9 and the other frontends.