Openlaszlo migration issues

Question

When i am trying to migrate the code from OL 3.3 to 4.9 i am getting this error. I have followed the steps mentioned here. http://wiki.openlaszlo.org/Runtime_Differences But still i am getting this error.

 [exec] Exception in thread "main" java.lang.NullPointerException
     [exec]     at org.openlaszlo.compiler.ClassModel.sortKey(ClassModel.java:235)
     [exec]     at org.openlaszlo.compiler.ClassModel.compareTo(ClassModel.java:244)
     [exec]     at java.util.TreeMap.put(TreeMap.java:560)
     [exec]     at java.util.TreeSet.add(TreeSet.java:255)
     [exec]     at java.util.AbstractCollection.addAll(AbstractCollection.java:334)
     [exec]     at java.util.TreeSet.addAll(TreeSet.java:312)
     [exec]     at java.util.TreeSet.<init>(TreeSet.java:160)
     [exec]     at org.openlaszlo.compiler.ViewSchema.resolveClassModels(ViewSchema.java:362)
     [exec]     at org.openlaszlo.compiler.Compiler.updateRootSchema(Compiler.java:809)
     [exec]     at org.openlaszlo.compiler.Compiler.compile(Compiler.java:452)
     [exec]     at org.openlaszlo.compiler.Compiler.compile(Compiler.java:199)
     [exec]     at org.openlaszlo.compiler.Main.compile(Main.java:463)
     [exec]     at org.openlaszlo.compiler.Main.lzc(Main.java:402)
     [exec]     at org.openlaszlo.compiler.Main.main(Main.java:105)

Has anyone come across the same type. Please let me know what is the solution.

Answer 1

The problem existed even in the 5.0 version but later by removing the dependencies one by one, i found that one of the class's default placement value is a constraint when i remove the constraint and give the proper name. The error was resolved.