DRT: com.google.common.base.VerifyException: null

[FNaqavi]

I got this error at iterations 20 of one run and 22 of another run of my DRT scenario. Any idea how to fix it?

This is my drt and dvrp settings for now:

<module name="multiModeDrt">
    <parameterset type="drt">
        <parameterset type="ExtensiveInsertionSearch"/>
        <param name="changeStartLinkToLastLinkInSchedule" value="true"/>
        <param name="drtServiceAreaShapeFile" value="./center1.shp" />
        <param name="maxTravelTimeAlpha" value="2.0"/>  
        <param name="maxTravelTimeBeta" value="900.0"/>
        <param name="maxWaitTime" value="600.0"/>
        <param name="operationalScheme" value="serviceAreaBased"/>
        <param name="stopDuration" value="10.0"/>
        <param name="vehiclesFile" value="drt_osm_2000.xml"/>
        <param name="writeDetailedCustomerStats" value="true"/>
        <parameterset type="zonalSystem">
            <param name="zonesGeneration" value="GridFromNetwork"/>
            <param name="cellSize" value="500"/>  
        </parameterset>
        <parameterset type="rebalancing">
            <parameterset type="minCostFlowRebalancingStrategy">
                <param name="targetAlpha" value="0.5"/>
                <param name="targetBeta" value="0.5"/>
            </parameterset>
        </parameterset>
        <parameterset type="drtfare">
            <param name="basefare" value="0"/>
            <param name="dailySubscriptionFee" value="34"/>
            <param name="distanceFare_m" value="0"/>
            <param name="timeFare_h" value="0"/>
            <param name="minFarePerTrip" value="0.0"/>  
        </parameterset>
    </parameterset>
</module>

<module name="dvrp">
    <parameterset type="travelTimeMatrix">
        <param name="cellSize" value="500"/>   
        <param name="maxNeighborDistance" value="1000"/>   
    </parameterset>
    <param name="networkModes" value="car"/>
    <param name="travelTimeEstimationAlpha" value="0.05"/>
</module>