QGIS on Windows: Oops … Could not load qgis_app.dll message

Sometimes after a Windows update, or after a QGIS update Windows users see the dreaded “Oops, looks like an error loading QGIS’… Could not load qgis_app.dll…” message

In short it means that one of the main libraries of QGIS cannot be fully loaded, because it is actually depending on other libraries, which (apparently) are not OK or available.

The 2 main reasons (I am aware of, please correct me if I am wrong), actually depend on your type of QGIS installation:

1) if you have installed QGIS with the “QGIS Standalone Installer” (the .msi version), the reason can be that the ‘opencl.dll’ version or install is messed up by Windows. For example see: https://answers.microsoft.com/en-us/windows/forum/all/opencldll-is-missing/de5a9687-c53d-4f33-8b28-47dc8115e745 As you can see it is not only QGIS having issues with it.

The solution is to make sure you have the good copy of opencl.dll either in the QGIS install dir OR in the c:/windows/system32 directory. See https://github.com/qgis/QGIS/issues/44806#issuecomment-908976764 for more info about it.

OpenCL is a framework to make it possible to share/move calculations to your graphics-card for parallel/faster processing: https://en.wikipedia.org/wiki/OpenCL.

(also check the second point below)

2) if you have installed QGIS using the OSGeo4W network Installer, the opencl.dll can also be a problem, BUT in that case there is sometimes an issue in which the scripts gis-bin.env or qgis-dev-bin.env files are vanished from your system. Those env files (in the QGIS/bin directory) are there to define the right PATH’s for QGIS and it’s libraries to find other libraries or elements needed.

As said sometimes (virus scanners?) do remove that script(s, one of each version of QGIS), so be sure those are there, or copy them from an other QGIS installation.

3) another opencl and QGIS related issue, see https://github.com/qgis/QGIS/issues/45507, is the one which tells you: “Can not find procedure entry point clCreateCommandQueueWithProperties in the DLL file C:\OSGeo4W\apps\qgis\bin\qgis_core.dll” or similar.

The solution to that is also to copy the right opencl.dll to make it available to QGIS again.

Hope this helps some people.

New PDOKServicesplugin (dutch public OWS services plugin)

Mostly interesting for dutchies: there is a new version of the PDOKServiceplugin, a plugin which makes it easier to set a WMS/WFS/WCS layer into QGIS from our national OWS services: PDOK.

Best addition for now: free High Resolution images of almost the whole of The Netherlands. To show of the old and the new version:

Wanne try yourself? Either install the plugin and search for “Luchtfoto 2021 Ortho HR” OR use the service url: https://service.pdok.nl/hwh/luchtfotorgb/wmts/v1_0?request=GetCapabilities&service=WMTS and search for that name (available in several CRS’s but our national one is EPSG:28992)

Institutional, centralized QGIS installation/configuration (QGIS.de)

QGIS more and more get’s to be installed ‘organisation wide’ by Windows Administrators (eg using SCCM, now Microsoft Endpoint Configuration Manager ), instead of personal installations by the GIS-people on their personal machines.

I get more and more questions about this (eg here)

So a short post about this. The good thing is that peeps from the QGIS user group Germany wrote a (also in english translated) page with A LOT of information and tips about how to do this. So I’m not going to copy that.

So for everybody wondering how to install QGIS with standard configuration or plugins:
READ https://qgis.de/doku.php?id=site:deployment:zentral_en . Thanks QGIS.de!

If you wonder about the loading order etc of all those settings, have a look into the code around here

Python development with PyCharm

Another pointing to… if you develop Python Plugins, and use PyCharm as IDE, read: about how to setup your IDE properly so PyCharm finds all QGIS and PyQt functions. Thanks Tudor!

Testing QGIS fixes on Windows

And as I am now crosslinking away, have a look at: https://github.com/qgis/QGIS/issues/39081
It shows the example about somebody having an issue, being fixed, and then being able to immediately test AND use the fix. By downloading that precise fixed QGIS. Very nice if you really really need that fix for your work TODAY. Disclaimer: in those QGIS applications NOT everybody is working (most notably Python stuff), it is not a full QGIS build like the ‘nightly builds’. Which are full installations of current development branch.

Happy QGIS-ing