TypeError when converting shapefiles to KMLs using PyQGIS

Question

In QGIS 3.16 I'm trying to load all shapefiles from a folder and subfolders and export all to KMLs files in a single folder (The shapefiles have different names).

This error appears, but I don't understand what I can do to resolve this:

TypeError: QgsVectorFileWriter.writeAsVectorFormat():
arguments did not match any overloaded call:
  overload 1: argument 1 has unexpected type 'str'
  overload 2: argument 1 has unexpected type 'str'
  overload 3: argument 1 has unexpected type 'str'

And the code is:

import os
    
input_folder = 'D:\python_dados_av1'
output_folder = 'D:\teste'
    
layers = [] 
for root, folder, files in os.walk(input_folder):
    for file in files:
        if file.endswith('.shp'):
            fullname = os.path.join(root, file)
            rename_shp = 'convert_%s' % (file)
            newfile = os.path.join(output_folder,rename_shp)
            layers.append(QgsVectorLayer(fullname, file.split('.')[0]))
            QgsVectorFileWriter.writeAsVectorFormat(file, newfile, "utf-8", "KML")

Answer 1

According to the documentation the first argument should be a QgsVectorLayer, which is why you are getting the unexpected type error.

You are also missing the QgsCoordinateReferenceSystem parameter.

This should work:

import os

layers = [] 
for root, folder, files in os.walk(input_folder):
    for file in files:
        if file.endswith('.shp'):
            fullname = os.path.join(root, file)
            rename_shp = 'convert_%s' % (file)
            newfile = os.path.join(output_folder,rename_shp)

            # assign the QgsVectorLayer you make to a variable which you can then pass to the QgsVectorFileWriter
            tmp_lyr = QgsVectorLayer(fullname, file.split('.')[0])
            layers.append(tmp_lyr)
            
            # get the CRS from the layer
            crs = tmp_lyr.crs()  
            QgsVectorFileWriter.writeAsVectorFormat(tmp_lyr, newfile, "utf-8", crs, "KML")