We have found out that action Tax\Declarations\Sales tax\Settle and post sales tax can duplicate records in table TaxTransGeneralJournalAccountEntry. Those duplicate records have reference to non existing TaxTrans records.

Based on our investigation, we think the issue in with variable taxReportVoucherTransCombine in class TaxReport. When SQL transient error occurs, it is catched in run method and posting is retried, but unposted and rollbacked data are still in variable taxReportVoucherTransCombine.

The variable is initialized only in constructor method new, but it should be initialized in method updateNow.