Error: At least one of the class levels is not a valid R variable name; This will cause errors when class probabilities are generated because the variables names will be converted.. By BylineEAL Salas on February 8, 2023February 15, 2023 The error message indicates that one or more of the levels in the class variable are not valid R variable names. When using R, variable names must start with aContinue readingError: At least one of the class levels is not a valid R variable name; This will cause errors when class probabilities are generated because the variables names will be converted..