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Medium severityschema

Power BI Refresh Error:
DM_GWPipeline_Gateway_DataTypeConversionError

What does this error mean?

A value retrieved from the data source could not be converted to the data type expected by the Power BI model. This typically happens when source data changes in a way that breaks type assumptions.

Common causes

  • 1A column that was purely numeric now contains text values (e.g., 'N/A', 'NULL', or empty strings)
  • 2A date column contains values in an unexpected format that cannot be parsed
  • 3A decimal column contains values exceeding the precision defined in the Power BI model
  • 4The source changed a column from one type to another (e.g., INT to VARCHAR) without updating the dataset
  • 5Locale-specific number formats (comma vs. period as decimal separator) causing parse failures

How to fix it

  1. 1Identify the specific column causing the error from the error detail — it usually names the column and value
  2. 2In Power Query Editor, add a step to handle nulls and errors: use Table.ReplaceErrorValues or try...otherwise
  3. 3Explicitly cast the column to the correct type in Power Query and handle edge cases (nulls, empty strings, 'N/A')
  4. 4If the source schema legitimately changed, update the column type in the Power BI model to match
  5. 5For date parsing issues, use Date.FromText() with an explicit format string rather than relying on locale inference

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