[Qgis-user] QGIS uninstalled after GDAL PPA install

[Andre Joost]

Am 28.02.20 um 18:29 schrieb J. M:

> Here's what I get:
> sudo apt-get remove libgdal20
> [sudo] password for jimi:
> Reading package lists... Done
> Building dependency tree
> Reading state information... Done
> Package 'libgdal20' is not installed, so not removed

That was expected, because apt-cache policy libgdal20 already told you 
that it was not installed.

> jimi at jimi-System-Product-Name:~$ dpkg -l | grep gdal
> ii  gdal-bin                                   3.0.2+dfsg-1~bionic2
>                      amd64        Geospatial Data Abstraction Library -
> Utility programs
> ii  gdal-data                                  3.0.2+dfsg-1~bionic2
>                      all          Geospatial Data Abstraction Library - Data
> files
> ii  libgdal26                                  3.0.2+dfsg-1~bionic2
>                      amd64        Geospatial Data Abstraction Library
> ii  python3-gdal                               3.0.2+dfsg-1~bionic2
>                      amd64        Python 3 bindings to the Geospatial Data


These are still GDAL 3.02 packages that you installed with the ubuntugis 
PPA. Get rid of those, otherwise you will not get further.

>
> I'm still not clear about what the ubuntugis PPA is needed for, or what
> gdal even is..

GDAL is more or less the heartbeat of QGIS. Almost every operation uses 
it. For some reason, you must use exactly the same GDAL version as the 
QGIS package is compiled against. For bionic (without ubuntugis), this 
is GDAL 2.2.3. The gdal-abi package is used to confirm that version.

With the Ubuntugis PPA, you have installed a newer version of GDAL 
(3.0.2), and the packet manager does not downgrade it by itself (it does 
not know about th specific QGIS requirements).


HTH,
Andre Joost