from pyscipopt import Model

model = Model()
matrix = model.addMatrixVar(3)
var = model.addVar()

model.addMatrixCons(matrix <= var + 1)  # Error!!!
# Traceback (most recent call last):
#   line 7, in <module>
#     model.addCons(matrix <= var + 1)  # Error!!!
#                   ^^^^^^^^^^^^^^^^^
#   File "src/pyscipopt/matrix.pxi", line 38, in pyscipopt.scip.MatrixExpr.__le__
# TypeError: Unsupported type <class 'pyscipopt.scip.Expr'>

matrix <= var  # OK

matrix <= matrix  # OK