Do I need to upgrade WIPO Sequence after WIPO ST.26 version 1.6 has come into force on July 1
No. There were no changes to the validation rules implemented in WIPO Sequence required after version 1.6 came into force. The differences between versions 1.6 and 1.5 of the Standard are only editorial in nature (clarifications, additional examples, correcting of formatting and grammatical errors etc.) Please continue to use version 2.3.0.