Hi,
what that means is that the set of instructions that do the work of homing your machine are calling for an axis (motor 0) that
is not enabled.
Have a look at Configure/Control/Axis Mapping per the attached. My machine has three axes, X,Y,Z and they are motors 0,1,2.
When my machine homes the homing instructions call for each to be homed.
You have two choices:
1) Enable the axis (motor) that is requested. Note this will prevent the error you have described but unless that axis (motor) is fitted
then it will never move and therefore never home and that's a fault too.
2) Change the homing (referencing) instructions to call only those axes (motors) that you have enabled and installed.
Just as a matter of interest, I haven't tried it but what would happen do you suppose if say you had motor 0 assigned to the X axis as I do
but don't have a X axis home switch assigned? I suspect that would give a similar error to that you have described.
Craig