Expression.Error: The key didn't match any rows in the table.
A row or record lookup (for example Source{[Name="X"]}) found no matching row.
Why it happens
- A sheet, table, or query name changed, so a navigation step points at nothing.
- A generated navigation key doesn't exist in the source.
- A merge/lookup key is missing on one side.
How to fix it
- Fix the navigation key to match the current object name.
- Make it tolerant:
Source{[Name="X"]}?returns null instead of erroring. - Verify the source object still exists and is spelled exactly (navigation is case-sensitive).
Fix
= Source{[Item="Sheet1",Kind="Sheet"]}?[Data]