Issue #1866: Query execution causes an unexpected internal exception (Error 990)

We have the following exception, why our query fails?

[ObjectDB 2.6.7_05] Unexpected exception (Error 990)
Generated by Java HotSpot(TM) 64-Bit Server VM 1.8.0_51 (on Windows 7 6.1).
Please report this error on http://www.objectdb.com/database/issue/new
com.objectdb.o.InternalException: null
com.objectdb.o.InternalException
at com.objectdb.o.InternalException.f(InternalException.java:236)
at com.objectdb.o.SPW.an(SPW.java:109)
at com.objectdb.o.PGW.aj(PGW.java:199)
at com.objectdb.o.UPT.C(UPT.java:134)
at com.objectdb.o.URT.l(URT.java:171)
at com.objectdb.o.TSK.i(TSK.java:145)
at com.objectdb.o.TSK.f(TSK.java:95)
at com.objectdb.o.TSM.e(TSM.java:86)
at com.objectdb.o.UTT.A(UTT.java:375)
at com.objectdb.o.UTT.l(UTT.java:223)
at com.objectdb.o.TSK.i(TSK.java:145)
at com.objectdb.o.TSK.f(TSK.java:95)
at com.objectdb.o.MST.Vt(MST.java:1350)
at com.objectdb.o.WRA.Vt(WRA.java:381)
at com.objectdb.o.WSM.Vt(WSM.java:153)
at com.objectdb.o.OBM.bS(OBM.java:984)
at com.objectdb.o.OBM.bP(OBM.java:852)
at com.objectdb.o.OBM.bO(OBM.java:783)
at com.objectdb.o.QRR.f(QRR.java:139)
at com.objectdb.jpa.JpaQuery.getResultList(JpaQuery.java:719)

The stack trace indicates an unexpected index state during a query update.

You should see some log lines starting at "Attempt to remove a non existing index entry" in the ObjectDB server log file. Could you please post these lines?

In addition, please check your database with the ObjectDB Doctor, and post the result report.