There was an error while initializing the numerical kernel

2021-03-19 14:25:45,842 INFO o.s.u.u.u.Ui2Num [] DONE
2021-03-19 14:25:45,906 ERROR o.s.u.u.c.NumTopFromUICommand [] Error in UI2NUM
java.lang.NullPointerException: null
at spis.Surf.SurfMesh.ThreeDUnstructSurfMesh.setVm( ~[org-spis-num-core-6.0.2.jar:6.0.2]
at org.spis.ui.ui2num.util.Ui2Num.buildNumTopFromUI( ~[org-spis-ui-ui2num-6.0.4.jar:6.0.4]
at [org-spis-ui-ui2num-6.0.4.jar:6.0.4]
at [org-spis-ui-ui2num-6.0.4.jar:6.0.4]
at org.keridwen.core.messaging.AbstractCommand.execute( [org-keridwen-core-messaging-3.0.10.jar:na]
at org.keridwen.core.messaging.DefaultBundleController$ [org-keridwen-core-messaging-3.0.10.jar:na]
at [na:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor.runWorker( [na:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor$ [na:1.8.0_202]
at [na:1.8.0_202]
2021-03-19 14:27:11,388 DEBUG BundleController:SPIS Model [] Change model state - org.spis.ui.simulation

I have seen this kind of error when there was errors in the group definition. In this case the mesh parameters may not be correctly parsed by UI and NUM has no mesh to initialize. Thus, you should check your group definition, and eventually rebuild a new simulation importing your mesh, circuit and global parameters but redefining from scratch the groups.

Thank you very much!