Thank you for your answers.
I found it is reported only in VIA4 by encounter, but when I run DRC in Calibre there are errors in other vias.(i.e. VIA1, VIA2, VIA3)
Finally I fixed the problem with shobhit's method by using Laker.
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I fixed the problem in Laker, but I want to ask how to setup the via in encounter?
I checked my technology LEF, there are many minimumcut rules defined in layers.
But they do not work when I do the nanoroute in ecounter.