MS-Fabric Cannot Preview or Query Delta Table

Fabric and Power BI can be picky with Delta tables, especially when you’re creating/overwriting them with notebooks.

What usually solves it:

• Explicitly define your schema in PySpark when writing your Delta table (don’t rely on Spark to infer from JSON or dynamic data). This makes sure the columns are always visible to downstream tools.
  
  

• Stick to simple types: Use String, Int, Double, Date, etc. Avoid nested or complex types Power BI just doesn’t like them yet.
  
  

• If you change the table’s schema, drop and recreate the table instead of just overwriting. Sometimes old metadata lingers and messes things up.
  
  

• Direct Lake connections in Power BI are generally more reliable than the SQL endpoints for previewing new/changed tables.
  
  

• If you get the “internal error” or [DELTA_READ_TABLE_WITHOUT_COLUMNS], it’s almost always schema mismatch or a type Power BI can’t read. Clean up the folder and rewrite can help if all else fails.
  
  

• There are also some ongoing Fabric bugs around metadata sync sometimes it’s just a matter of waiting a few minutes or doing a manual metadata refresh in the portal.