Sometime around January 15, 2021 a change was made to the List Rows action in the Excel Online (Business) connector that stopped bringing dates in as Serial dates and started bringing them in as ISO 8601 formatted strings. If you have existing flows that were written prior to January 15th there is a good chance that this change will break your flow. This blog will explain the background behind Serial dates in Excel, explain what you can expect going forward for Excel fields formatted as dates, and provide some helpful formulas that will let you convert dates if necessary.