Q: I got an error shown as above (output from different solver). What is the possible reason for this error?
Your model contains at least one variable with a coefficient in the objective but otherwise it does not show up in the constraint matrix (at least after preprocessing). The sign of the coefficient in the objective and the type of the variable (positive, negative, free) allows the model to become unbounded (or dual infeasible). Check the output for variables, which have a very large level, set a bound on the suspicious variables and see why it is not restricted by other parts of the model.