I have a field with a bunch of species names, but for a single species there a bunch of case combinations (e.g. Cat, CAT,cat). I want to make a new field which has all the entries in all lower case. I tried using the field calculator with the script = !SPECIES!.lower() but keep getting ERROR 000539.

Anyone have any idea where I am going wrong?

  • 2
    with the above do you have the python radio checked?
    – Brad Nesom
    Feb 8, 2014 at 18:52
  • 2
    In what format is the data stored? (Please update the question, and include the version of ArcGIS in the body while you have the chance)
    – Vince
    Feb 8, 2014 at 18:55

1 Answer 1


the syntax !SPECIES!.lower() is a correct Python statement. The type of your input field is obviously text so the problem is not there. Of course you need to check the Python box as suggested by @Brad, but error 539 is usually associated with Python (so I think you did).

The source of the problem is therefore most probably in the output field type. Check that it is "text" and that the length is large enough to store your names. Note that you could also make the computation in the field itself, but it is then recommended to work in an edit session in order to have the possibility to go back.

Just for completness, the vb script would be :


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