I have an existing SmartConnect map that is pointing to an Excel file. If I add a new column to that file, I receive the error message ‘Object reference not set to an instance of an object’ when I click validate or preview. The map was working until I added the new column.

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The issue is there is an existing column with the same name already mapped via a local constant. I added a column to my Excel file called MYBATCH but the local constant called MYBATCH was already mapped in the destination. If I changed the local constant or change the column in the Excel file, the map will open and run correctly.

The same issue will occur for any type of data source, if you add a new column to that data source that matches an existing column, whether it’s a local constant, global constant or any additional column name.