<![CDATA[Configure script for Qt5.15.X fails on Linux-Ubuntu24 with "Could not find qmake spec ''"]]>Hello everyone,

I'd like to compile a version of Qt5.15.X on a fresh Linux-Ubuntu24. Qt5.15.13 is (still) packaged for Ubuntu24, so it is clearly possible.

AFAIK, I have installed all the dependencies I am aware of.

However, no matter which Qt5.15 version of qt sources I download (I tried Qt5.15.2, Qt5.15.13, Qt5.15.15, Qt5.15.18), the configure script aborts with the following error :

+ cd qtbase
+ XXX/qt-everywhere-src-5.15.15/qtbase/configure -top-level 
Creating qmake...
.Done.
Could not find qmake spec ''.
Error processing project file: XXX/qt-everywhere-src-5.15.15/qt.pro

I am clearly missing something, likely a needed dependency, but... well... I could bot figure out the problem.

Would you have a hint for me ?

Thanks in advance,
N.

]]>https://forum.qt.io/topic/164273/configure-script-for-qt5.15.x-fails-on-linux-ubuntu24-with-could-not-find-qmake-specRSS for NodeFri, 08 May 2026 07:08:07 GMTMon, 16 Feb 2026 11:03:59 GMT60<![CDATA[Reply to Configure script for Qt5.15.X fails on Linux-Ubuntu24 with "Could not find qmake spec ''" on Fri, 20 Feb 2026 11:48:05 GMT]]>Accents and spaces are pretty tricky !
Glad you found out and thanks for sharing

]]>https://forum.qt.io/post/836450https://forum.qt.io/post/836450Fri, 20 Feb 2026 11:48:05 GMT<![CDATA[Reply to Configure script for Qt5.15.X fails on Linux-Ubuntu24 with "Could not find qmake spec ''" on Tue, 17 Feb 2026 11:45:18 GMT]]>Hello again.

Well, problem solved !

My qt-everywhere-src-5.15.XX directory was placed behind a path with French accents (eg $HOME/Téléchargements).

Accents (and very likely other non-ASCII chars) within the qt source directory's path is not supported by the configure script.

My configure script ran OK :)

Thanks

]]>https://forum.qt.io/post/836350https://forum.qt.io/post/836350Tue, 17 Feb 2026 11:45:18 GMT<![CDATA[Reply to Configure script for Qt5.15.X fails on Linux-Ubuntu24 with "Could not find qmake spec ''" on Tue, 17 Feb 2026 11:37:26 GMT]]>Hello and thanks.

@SGaist no I am not.

This is exactly what I do (with various qt5.15 source versions) :

  • download the sources from the Qt archives, eg https://download.qt.io/archive/qt/5.15/5.15.18/
  • navigate to the qt-everywhere-src-5.15.18 directory
  • run the configure script, with e.g. ./configure -prefix $PWD/qtbase -opensource -nomake tests

This is when the configure script generates the error. Full output is :

+ cd qtbase
+ XXX/qt-everywhere-src-5.15.15/qtbase/configure -top-level 
Creating qmake...
.Done.
Could not find qmake spec ''.
Error processing project file: XXX/qt-everywhere-src-5.15.15/qt.pro

An internet search indicates that I may be missing some dependencies on my freshly installed Ubuntu24.
But which one ? I can't figure out.

Thanks;
Nicolas

]]>https://forum.qt.io/post/836348https://forum.qt.io/post/836348Tue, 17 Feb 2026 11:37:26 GMT<![CDATA[Reply to Configure script for Qt5.15.X fails on Linux-Ubuntu24 with "Could not find qmake spec ''" on Mon, 16 Feb 2026 19:41:53 GMT]]>Hi,

Are you doing an out of source build ?

]]>https://forum.qt.io/post/836334https://forum.qt.io/post/836334Mon, 16 Feb 2026 19:41:53 GMT