Exception in thread "main" java.lang.ClassCastException: cc.mallet.types.FeatureSequence cannot be cast

[findgit123]

how to solve this below: i am using latest Mallet-202108 downloaded here
C:\Users\4>mallet import-dir --input D:\test_mallet\input\ --output D:\test_mallet\data.mallet --keep-sequence --remove-stopwords
Labels =
D:\test_mallet\input
C:\Users\4>mallet train-classifier --input D:\test_mallet\data.mallet --output-classifier D:\test_mallet\my.classifier
Training portion = 1.0
Unlabeled training sub-portion = 0.0
Validation portion = 0.0
Testing portion = 0.0

-------------------- Trial 0 --------------------

Trial 0 Training NaiveBayesTrainer with 639 instances
Exception in thread "main" java.lang.ClassCastException: cc.mallet.types.FeatureSequence cannot be cast to cc.mallet.types.FeatureVector
at cc.mallet.classify.NaiveBayesTrainer.incorporateOneInstance(NaiveBayesTrainer.java:274)
at cc.mallet.classify.NaiveBayesTrainer.trainIncremental(NaiveBayesTrainer.java:202)
at cc.mallet.classify.NaiveBayesTrainer.train(NaiveBayesTrainer.java:191)
at cc.mallet.classify.NaiveBayesTrainer.train(NaiveBayesTrainer.java:57)
at cc.mallet.classify.tui.Vectors2Classify.main(Vectors2Classify.java:446)
C:\Users\4>