FTS AbstractMethodError

on platform-6.6.1 I get this error when on reindexAll() invoke

Operation invoked successfully with result:

java.lang.IllegalArgumentException: Directory MMapDirectory
@C:\Users\\deploy\tomcat\work\app-core\ftsindex lockFactory=org.apache.lucene.store.NativeFSLockFactory@4eaed998
still has pending deleted files; cannot initialize IndexWriter

Also when I choose the FTS condition on filter it throws a error

AbstractMethodError: com.haulmont.fts.app.FtsFilterHelperBean.createFtsWhereClause(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;

The problem was fixed in the 6.9.0 version. See issue: https://youtrack.cuba-platform.com/issue/PL-9591

AbstractMethodError: com.haulmont.fts.app.FtsFilterHelperBean.createFtsWhereClause(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;

Try to drop tomcat and start project again.

I drop the tomcat and started the project again but the error is still there

when I try to search in fts also this error is thrown

AbstractMethodError: com.haulmont.fts.app.FtsFilterHelperBean.createFtsCondition(Ljava/lang/String;)Lcom/haulmont/cuba/gui/components/filter/condition/CustomCondition;

Could you reproduce the error on a new project?
I have tried to reproduce on 6.6.1, but it works.

AbstractMethodError occurs only if FTS and CUBA have different versions.