Thank you for taking a look at my code. Unfortunately, I could not solve the problem with the code you provided. The code and error are as follows:import arcpy, os
from arcpy import env
env.workspace = os.getcwd()
mxd = arcpy.mapping.MapDocument(env.workspace + r"\CoastalCurrentsData.mxd")
# Dataframe stuff - perform an arcpy.mapping UpdateLayer (using the above pre-authors layer file)
df = arcpy.mapping.ListDataFrames(mxd, "CoastalCurrentsData")[0]
updateLayer = arcpy.mapping.ListLayers(mxd, "RecentData", df)[0]
sourceLayer = arcpy.mapping.Layer(env.workspace + "/USWC_1km_WGS_1984.lyr")
arcpy.mapping.UpdateLayer(df, updateLayer, sourceLayer, True)
# Refresh the layers unique value symbology so that it is referencing the current data
# HERE'S WHERE THE ERROR HAPPENS #######
sourceLayer.symbology.addAllValues()
# AttributeError: 'Layer' object has no attribute 'symbology'
arcpy.RefreshActiveView()
arcpy.RefreshTOC()