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

[Alessandro Pasotti]

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
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>>
>

-- 
Alessandro Pasotti
QCooperative:  www.qcooperative.net
ItOpen:   www.itopen.it
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