[QGIS-Developer] Building QGIS with QT6 on Ubuntu: Python error at start

[Werner Macho]

Hi Alessandro,
Interesting, for me it was debian testing (first with some qt5 packages
also installed) - and than a fresh install with only qt6 packages (because
I thought the problem might come from "old" accidentally included qt5
packages.
I will try another fresh install with debian stable (currently still V12)
and see if it works there.
Otherwise my assumption would still be some corrupt qt6 development
packages in debian but I don't want to blame anyone before being sure.

regards
Werner

On Mon, Jul 21, 2025 at 5:09 PM Alessandro Pasotti <apasotti at gmail.com>
wrote:

> Hi Werner,
>
> The error I see is when I am building QGIS with QT6 on Ubuntu 25.04 (but I
> also tried 24.10 with the same result).
>
>
>
> On Mon, Jul 21, 2025 at 5:04 PM Werner Macho <werner.macho at gmail.com>
> wrote:
>
>> Hi Alessandro,
>> Nice to see another one having the same problem.
>> On which linux distribution are you?
>> I am using debian testing -  and despite having it installed again from
>> scratch I have the same problem (though nothing from qt5 installed the
>> second time).
>> Probably a problem in the debian package?
>> It was not urgent for me so I did not report it yet.
>>
>> regards
>> Werner
>>
>> On Mon, Jul 21, 2025 at 4:58 PM Alessandro Pasotti via QGIS-Developer <
>> qgis-developer at lists.osgeo.org> wrote:
>>
>>> Hi,
>>>
>>> I am trying to build QGIS with QT6 on Ubuntu (tried 24.10 and 25.04),
>>> it builds without errors but when I run it, the following error appears:
>>>
>>> Couldn't load PyQGIS.
>>> Python support will be disabled.
>>>
>>>
>>> Traceback (most recent call last):
>>>   File "", line 1, in
>>>   File "/home/ale/dev/QGIS/build/Desktop_QT6-Debug/output/python/qgis/gui/__init__.py", line 25, in
>>>     from qgis._gui import *
>>> RuntimeError: qgis._gui cannot import type '���A� ' from PyQt6.QtCore
>>>
>>> Python version:
>>> 3.13.3 (main, Jun 16 2025, 18:15:32) [GCC 14.2.0]
>>>
>>> QGIS version:
>>> 3.99.0-Master 'Master', e717e3cd2b9
>>>
>>> Python path:
>>> ['/home/ale/dev/QGIS/build/Desktop_QT6-Debug/output/python',
>>> '/home/ale/.local/share/QGIS/QGIS3/profiles/default/python',
>>> '/home/ale/.local/share/QGIS/QGIS3/profiles/default/python/plugins',
>>> '/home/ale/dev/QGIS/build/Desktop_QT6-Debug/output/python/plugins',
>>> '/home/ale/dev/gdal/desktop-install/local/lib/python3.13/dist-packages',
>>> '/home/ale/dev/gdal/autotest/pymod', '/usr/lib/python313.zip',
>>> '/usr/lib/python3.13', '/usr/lib/python3.13/lib-dynload',
>>> '/usr/local/lib/python3.13/dist-packages', '/usr/lib/python3/dist-packages']
>>>
>>>
>>> I checked the QGIS/build/Desktop_QT6-Debug/output/python/qgis content
>>> and it looks legit.
>>>
>>> PyQt6 installation also looks ok, importing core works ok, only gui does
>>> not work.
>>>
>>> Any idea about what's going wrong?
>>>
>>>
>>> --
>>> Alessandro Pasotti
>>> QCooperative:  www.qcooperative.net
>>> ItOpen:   www.itopen.it
>>> _______________________________________________
>>> QGIS-Developer mailing list
>>> QGIS-Developer at lists.osgeo.org
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>>>
>>
>
> --
> Alessandro Pasotti
> QCooperative:  www.qcooperative.net
> ItOpen:   www.itopen.it
>
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