Hi Daniel,
I think there is some confusion.
The acados_ocp_solver is generated purely based on the information given in acados_ocp.
The acados_ocp_solver.set() function is only meant to be used to interact with the solver, not with acados_ocp.
You can only set stage wise parameter values in an existing solver currently. which you are doing correctly though in your snippet.
Also, .generate() and .build() are classmethods and supposed to be used like here: acados/time_optimal_example.py at master · acados/acados · GitHub
I hope this clarifies it!