conversion from .kml to .pln or .flt files

[routeconverter]

Mar 28, 2021 6:54:32 PM slash.navigation.converter.gui.panels.ConvertPanel saveFiles
SEVERE: Error saving C:\Users\jarol\Documents\Barbados.pln in slash.navigation.msfs.MSFSFlightPlanFormat@54553cb5: java.lang.IllegalArgumentException: Cannot format given Object as a Number, java.lang.IllegalArgumentException: Cannot format given Object as a Number
at java.text.DecimalFormat.format(Unknown Source)
at java.text.Format.format(Unknown Source)
at slash.navigation.msfs.MSFSFlightPlanFormat.formatElevation(MSFSFlightPlanFormat.java:130)
at slash.navigation.msfs.MSFSFlightPlanFormat.createSimBaseDocument(MSFSFlightPlanFormat.java:168)

was the magic part of the log that I was searching for.

So your input file has no elevation information and now I'm using 0.0 when writing the flight plan file now. Please test the latest prerelease I've just uploaded.