[GIS] Fiona ImportError: DLL load failed

fionaimporterror

I've been using the great Shapely/Fiona combo successfully on Linux, but now i need to create a kind of production environment on windows and theres only one problem. When i try to import fiona, i get the following error:

Import DLL error

if i try to check dependancies of the ogrext.pdy using dependancy walker, it seems it is trying to load GDAL version 1.10 dll and fails. Strangely though, i have GDAL 1.9.2 installed and it seems to import into python without a problem (from osgeo import gdal). So maybe its not even related to the fiona import issue. Also, im 100% i downloaded the fiona installer for python 2.7 since i know issues can arise if you use .pyd files intended for a different version of python.

Note, im using a standalone installation of python 2.7.5, without using osgeo4w installer.

Best Answer

This ongoing issue used to be caused by Fiona being incompatible with GDAL, but Fiona has been updated, so the below answers may be more relevant.

Fiona 1.8.9 supports GDAL 3.0

Documentation:

A shim module and support for GDAL 3.0 has been added. The package can now be built and used with GDAL 3.0 and PROJ 6.1 or 6.2. Note that the 1.8.9 wheels we will upload to PyPI will contain GDAL 2.4.2 and PROJ 4.9.3 as in the 1.8.8 wheels.

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[GIS] How to Setup Python to recognize QGIS

It looks like you have a similar problem to one I had. Though the specifics of the paths are different I believe that a similar solution can work. See my solution in this post.

What is happening is that it is not just the PYTHONPATH which is read but also the PATH variable. On load QGIS appends the paths of the osgeo binaries to the path, which means they get read last. That means the ArcGIS location is found first and Windows looks no further.

What you don't want to do is muck up your ArcGIS install by playing with the main PATH variable (where there will be a reference to the Arc Python directory). However, if you tell QGIS to reverse the sys.path variable as the first thing it does, it will read the osgeo paths first and ignore the Arc Python instalation. This change is only apparent within the specific Python session (i.e. it has no effect on the actual PATH or PYTHONPATH variables stored on your computer and neither is it permanent, so will be safe as far as ArcGIS is concerned and less dangerous than editting your PATH variable as this could end up breaking Arc with the same problem but the other way around).

Depending on your install, you might want to change my solution to something like (based on what I read in your question):

import sys
sys.path.extend([r"C:\Quantum_GIS_Lisboa\apps\qgis\python",r"C:\Quantum_GIS_Lisboa\apps\qgis\bin"])
sys.path.reverse()

If you have used osgeo4w to install QGIS this will be unnecessary, but you could do it anyway as a belt-and-braces approach - it won't hurt). I suspect you will also need to add the lines at the start of the set_qgis_01.py file (I did mine in the GDALTOOLS.py file because that's where my conflict manifested itself).

[GIS] Conflict between ArcPy and GDAL/OGR

I suspect the issue is the GDAL 1.11 bindings you're fetching from gohlke do not match the internal GDAL inside of Arc*. Your bindings need to be compiled against ESRI's GDAL to work reliably. It's possible they can be made to work, but it is going to be a lot of headache.

In short, ESRI needs to provide the gdal_i.lib stub file that GDAL generates as part of its compilation process, and you need to build the Python bindings against that. I don't know that ESRI provides this, however.

Maybe ESRI could be requested to provide a gdal.py and GDAL bindings as part of ArcPy? Alternatively, maybe you could use Fiona and rasterio to replicate the GDAL bindings parts you need. These have the benefit of not needing to link against the ESRI GDAL and instead are able to use it by doing C API calls directly into the DLL.

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[GIS] How to Setup Python to recognize QGIS

[GIS] Conflict between ArcPy and GDAL/OGR

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