For all structures the reassigning of friction_type 4 to 2 needs to be removed (this is very old legacy). We now have a meaningful friction_type 4 (manning_conveyance), so conversion will lead to problems.
Note: Probably only the testbank will have friction_types 4 that do not mean manning_conveyance. Please check!
https://github.com/nens/threedigrid-builder/blob/43f878c50cb972f5a51a2401913ec7bb803c4d48/threedigrid_builder/interface/db.py#L539
For all structures the reassigning of friction_type 4 to 2 needs to be removed (this is very old legacy). We now have a meaningful friction_type 4 (manning_conveyance), so conversion will lead to problems.
Note: Probably only the testbank will have friction_types 4 that do not mean manning_conveyance. Please check!