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Error: Failed to alter spatial reference

Error Message

When adding an 'Undefined' raster to ArcMap and defining the projection using ArcToolbox > Data Management Tools > Projections and Transformations > Define Projection, the following error message occurs:

"Failed to alter spatial reference.
The dataset already has a projection defined.
Failed to execute."

Cause

The .aux file is created when adding the image to ArcMap. The .aux file stores the coordinate system of the image and ArcMap reads 'Undefined' as an actual coordinate system.

Solution or Workaround

The solution is to define the projection by using the appropriate coordinate system, as follows.

  1. Close ArcMap and start ArcCatalog.
  2. Go to ArcToolbox > Data Management Tools > Projections and Transformations > Define Projection.
  3. Browse to the raster for the Input Dataset.
  4. Select a coordinate system.
  5. Run the tool; it should execute successfully.