Merging List of shapefiles gives ERROR 000400? [closed]

Question

I'm trying to create a list of shp that are within my map and get the pathname of each shp so I can then add it as an attribute. Within the process I want to merge them and that's where I'm getting an error line 16:

Failed to execute. Parameters are not valid. ERROR 000400: Duplicate inputs are not allowed Failed to execute (Merge).

I'm not sure if this due because my shp. have almost the same name or if it's something within my code. I must say I'm quite new to python so not really sure what I'm missing.

This is the script I'm using:

Answer 1

It seems you're going through your layers looking for shape files but not doing anything when you find them.. consider doing it this way:

output=r'N:\Path'
mxd = arcpy.mapping.MapDocument(r'N:\Path') # this isn't a mxd

PolyShapes = [] # an empty list
for layer in arcpy.mapping.ListLayers(mxd):
    if layer.valid(): # layer is not broken
        if layer.isFeatureLayer: # is a feature layer not a group or raster layer
            if '.shp' in layer.dataSource.lower():
                d=arcpy.Describe(layer.dataSource)
                if d.shapeType=='Polygon': 
                    if layer.dataSource not in PolyShapes:
                        PolyShapes.append(layer.dataSource)

arcpy.Merge_management(PolyShapes,os.path.join(output,'All_Boundaries.shp'))

Start with an empty list then iterate the layers, check the layer is valid (points to a dataset) and is a feature layer, then ensure it's a polygon shapefile using the describe object then add to the list (if not there already) then finally merge using the list.