I am learning five mlogits as follows

v1.model<-mlogit(v1~1|v2+v3+v4+v5, data=mlogit.v1.data, reflevel="1")
v2.model<-mlogit(v2~1|v1+v3+v4+v5, data=mlogit.v2.data, reflevel="1")
v3.model<-mlogit(v3~1|v1+v2+v4+v5, data=mlogit.v3.data, reflevel="1")
v4.model<-mlogit(v4~1|v1+v2+v3+v5, data=mlogit.v4.data, reflevel="1")
v5.model<-mlogit(v5~1|v1+v2+v3+v4, data=mlogit.v5.data, reflevel="1")

v2 and v5 give me the error below during learning, the other 3 models work
fine

"Error in solve.default(H, g[!fixed]) : system is computationally singular:
reciprocal condition number = 1.12239e-16"

What does this error mean?

Thanks

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