I have a weird problem. I have a feature class generated from processing multiple rasters and converted by Raster to polygon tool in ArcGIS 10.4.

I would like to apply Unique value symbology based on field gridcode in ArcMap. The individual gridcode values (from 0 to 14) exist in the field gridcode in Attribute table, I can also Label them, as here:

Unique labels of gridcode

However, when I want to apply Unique value symbology, only the value "1" gets load after "Add all values".

After loading "Add all values" symbology, the unique values are not loaded

Do you know why the other values do not get loaded?

  • 1
    Are the statistics for the raster built? If not use calculate statistics with skip of 1, 1 to ensure correct statistics are set for the raster. From memory 'Add all values' only reads the first 10000 values to establish valid values, but that might just be for attribute tables. Nov 12, 2017 at 21:50
  • She is dealing with polygons. I'd use new mxd with that layer only.
    – FelixIP
    Nov 12, 2017 at 22:01
  • 2
    It could be a known problem @FelixIP, it sounds like the sample size is reached before the end of records. There is a workaround for it support.esri.com/en/technical-article/000004373, assuming the layer isn't definition queried to just the one value. Nov 12, 2017 at 22:03
  • Thank you, I tried to adjust sample size to 25.000 (24.177 is the number of my polygons), but it did not helped. I'll try ti re-run my model
    – maycca
    Nov 13, 2017 at 1:32

2 Answers 2


My problem consisted in a fact, that I had two fields in the attribute table with same alias: gridcode. (even if the Field names were different: gridcode and gridcode_1)

When I have modified the alias of one of those (gridcode -> gridcode_1), then it magically worked!

My answer is based on comments of @BERA, published here: Two fields have same name in attribute table and not possible to get unique values?


What worked for me was setting the primary display field to the field I wanted to classify values by, then removing and re-loading the raster to the map.

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