Hi @qianpu1605, as leetleyang said, this is probably a bug in CryoSPARC v4.5. The bug has now been fixed and the fix was released today as part of a CryoSPARC patch.
This is a different error, actually - it’s saying that you have no movies with at least 2 particles. Is it possible that you connected movies and particles that don’t correspond to each other? Particles “remember” which movies they were extracted from, and this information is necessary for RBMC, local motion, extraction, etc, to work correctly. The “reassign particles to micrographs” job can be used to transfer particles from one set of movies to another.
Note that if you import one set of movies twice, even if they’re the same physical movies, they’re treated as different movies in cryosparc. So suppose you have a set of movies, if you import them twice (imports A and B), and extract particles from A, but then connect those particles and movie set B to RBMC, you would see this error.