The Falcon 9 - Amos-6 - mission in 3 September 2016 failed before launch - the rocket exploded during the static fire test.
Some lists contain such missions but others don't - like for example Jonathan C. McDowell's JSR launch database.
What other such missions failed before launch? I mean catastrophic failures that end in the loss of the rocket
The list include:
- after ignition but before release of clamps
- test ignition a day or two or more before launch
- during count-down count