Python code execution error in QGIS WIEN

Question

I have tried to make several different actions in QGIS but keep getting similar error messages when I try to select the output filename. The error message reads as follows:

An error has occurred while executing 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/doVectorGrid.py", line 333, 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'

Python version: 2.7.10 (default, Oct 23 2015, 19:19:21) [GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] QGIS version: 2.14.3-Essen Essen, exported

Python Path: /Users/nickjames/.qgis2/python/plugins/postgis_geoprocessing /Applications/QGIS.app/Contents/MacOS/../Resources/python/plugins/processing /Users/nickjames/.qgis2/python/plugins/pktools /Applications/QGIS.app/Contents/MacOS/../Resources/python /Users/nickjames/.qgis2/python /Users/nickjames/.qgis2/python/plugins /Applications/QGIS.app/Contents/MacOS/../Resources/python/plugins /Library/Frameworks/SQLite3.framework/Versions/C/Python/2.7 /Library/Frameworks/GEOS.framework/Versions/3/Python/2.7/site-packages /Library/Python/2.7/site-packages/numpy-override /Library/Python/2.7/site-packages/matplotlib-override /Library/Frameworks/GDAL.framework/Versions/1.11/Python/2.7/site-packages /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7 /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC /Library/Python/2.7/site-packages /Users/nickjames/.qgis2//python /Applications/QGIS.app/Contents/Resources/python/plugins/fTools/tools /Users/nickjames/Desktop/qgis

This particular error was in response to trying to create a vector grid and when clicking the browse button for the 'output shapefile' button this error came up. This may seem like a repeat question but on other threads no working solution was given for my situation.

I am running QGIS ESSEN (2.14) on a macbook pro which I just re-installed in an attempt to fix the problem but to no avail

Answer 1

This error is a Qgis bug,on a macbook platform,actually.

https://hub.qgis.org/issues/14682

Answer 2

As this was marked as a software bug, there's not much to do until it's fixed. But an alternative solution to the particular problem I was facing is very simple and maybe even easier than the proposed original plan.

I was trying to create a raster that reflected the frequency of intersections it had with my point vector layer (this was to show where recorded disturbances were concentrated within a forested area). In other words how many dots were within a said radius or pixel. My solution, provided that you don't need to much control over the classification was to just simply use a heat map, playing around with the radius until you get something meaningful and interpretable. For my sample area of approximately 50km squared i used a radius of 25 pixels. This is done through the layer properties>style options.