How can I change multistage nlmpc Solver?

I am trying to change nlmpcMultistage object solver from 'fmincon' to 'gmres' following this guide: https://www.mathworks.com/help/mpc/ug/control-robot-manipulator-using-cgmres-solver.html

However, I receive the following error:

"Error using nlmpcMultistage/set.Optimization

Invalid field name "Solver" found in the "Optimization" structure."

I also tried a suggestion such as to initialize the object with the Solver argument specified as: nlmpcMultistage(p,nx,'MV',1,'MD',2,'Solver','cgmres');

However I get the following error: Error using nlmpcMultistage

Input channel must be one of the following types: 'MV' (manipulated variable), 'MD' (measured

disturbance), or 'UD' (unmeasured disturbance).

Like the Solver option is not available.

Is there a way to change the solver to cgmres?

Thanks in advance