Desktop connected to Dataflow Gen2 Key didn't match row Error

Hi jessimica1018 , Thank you for reaching out to the Microsoft Community Forum.

Since disconnecting/reconnecting and moving transformations to the Dataflow didn’t fully work, let’s try below:

Verify the `Assignment` table by running this SQL query in SQL Server: SELECT TABLE_NAME, COLUMN_NAME, DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Assignment'. Then, in Dataflow Gen2, right-click the "Navigation" step, select "Refresh Preview," or use "Refresh Schema" to update metadata. To fix the intermittent error due to concurrency, schedule your Dataflow refresh during low-activity periods. If the table changes often, create a staging table in SQL Server with stable data and query that instead.

For the slowness, push the `Text.ToLower` transformation to SQL Server with this view: CREATE VIEW vw_Assignment AS SELECT LOWER(AM_Email) AS AM_Email, LOWER(Rec_Email) AS Rec_Email, LOWER(CM_Email) AS CM_Email, * FROM Assignment. Connect your Dataflow to `vw_Assignment`.Further optimize by applying early filters to reduce data volume, enabling "Enhanced Compute Engine" in Dataflow settings, adding indexes to the `Assignment` table’s email columns, and ensuring your On-Premises Data Gateway runs on a high-performance machine. Test the refresh to confirm the error is gone and load times are better.

If none of the above work, the best next step is to report the issue to Microsoft Support, as it may be a bug or a backend issue. Provide them with all the troubleshooting steps you've already taken to help them understand the issue better and provide a solution.
 

If this helped solve the issue, please consider marking it 'Accept as Solution' so others with similar queries may find it more easily. If not, please share the details, always happy to help.
Thank you.