Good morning,

I use the latest version of QGIS (Lyon) in MAC and have se the default Python version 2.7. Moreover, I have installed all the required python modules and GDAL.

It was working before, but now, when I click on the "Browse" button in Vector-> Geoprocessing->Union, it returns the following error (actually, it returns this error whenever I click on any "browse" button in QGIS):

Error during execution of Python code :

TypeError: QgsEncodingFileDialog(QWidget parent=None, QString caption=QString(), QString directory=QString(), QString filter=QString(), QString encoding=QString()): argument 3 has unexpected type 'QPyNullVariant' 
Traceback (most recent call last):
  File "/Applications/QGIS.app/Contents/Resources/python/plugins/fTools/tools/doGeoprocessing.py", line 125, in outFile
    (self.shapefileName, self.encoding) = ftools_utils.saveDialog(self)
  File "/Applications/QGIS.app/Contents/Resources/python/plugins/fTools/tools/ftools_utils.py", line 327, in saveDialog
    fileDialog = QgsEncodingFileDialog(parent, QCoreApplication.translate("fTools", "Save output shapefile"), dirName, filtering, encode)
TypeError: QgsEncodingFileDialog(QWidget parent=None, QString caption=QString(), QString directory=QString(), QString filter=QString(), QString encoding=QString()): argument 3 has unexpected type 'QPyNullVariant'


Versione Python: 2.7.10 (default, Oct 23 2015, 18:05:06) [GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] 
Versione di QGIS: 2.12.1-Lyon Lyon, exported 


I cannot enter the path manually. It does not allow me to click in the blank field.

Thanks for every answer,
Marta