How to upgrade Qt from 5.14.2 to 5.15.1 ?

mariozio

Hello to everyone.

I'm on ubuntu 20.10 and I've installed KDE Plasma. Below you can see the Qt version that has been also installed :

root@ziomario-z390aoruspro:/opt# qmake --version

QMake version 3.1

Using Qt version 5.14.2 in /usr/lib/x86_64-linux-gnu

but this Qt version is not enough high for me. Infact it should be upgraded to 5.15.1,according with this tutorial :

https://community.kde.org/Plasma/Wayland/Nvidia

where it says :

You need a very up-to-date Qt. Make sure you have >= Qt5.15.1 or 4bd13402f0293e85b8dfdf92254e250ac28094c7 cherry-picked. This Qt version is necessary to enable Wayland on top of Kde Plasma.

I've upgraded it using this file : qt-unified-linux-x64-3.2.3-online

that I've got from here : https://download.qt.io/archive/online_installers/3.2/

the problem is that it didn't work. It has installed all the libraries into /opt/Qt/5.15.1 folder,but when I check which version of Qt I'm running,I see that it hasn't changed :

Using Qt version 5.14.2 in /usr/lib/x86_64-linux-gnu

what's missing ?

sierdzio

You can install Qt to system folders, or add symlinks in /usr/lib pointing to your newer version.

But I don't recommend it at all. Qt shipped with given distribution has been compiled and tested to work with other apps shipped by the distro. If you swap Qt version you may run into a myriad of problems, crashes etc. in many random apps.

Best approach: find a PPA which ships updated KDE & Qt (KDE Neon comes to mind here) or switch to a different distribution which ships with modern enough Qt.

mariozio

@sierdzio said in How to upgrade Qt from 5.14.2 to 5.15.1 ?:

PPA which ships updated KDE & Qt (KDE Neon

what about to compile them from scratch like this ?

http://www.linuxfromscratch.org/blfs/view/svn/x/qt5.html

sierdzio

Even there, they recommend installing to /opt ;-)

But look further down, they provide installations on how to tell the system where to look for Qt instead of scanning /usr.

Feel free to try it, sure. Or custom compilation - that's surely possible. My warning still stands - you are likely to break your system. It's a good training and adventure, though :-) Please report back if you make any progress.

mariozio

yes. I understand. I don't have the competence to solve the problems that will come.

SGaist

Hi,

What distribution are you currently using on your machine ?

sierdzio

@SGaist said in How to upgrade Qt from 5.14.2 to 5.15.1 ?:

Hi,

What distribution are you currently using on your machine ?

See first post: I'm on ubuntu 20.10

SGaist

@sierdzio thanks, I completely missed it.

If you want to go with the latest and greatest of Plasma, then you should consider using KDE Neon. It's an Ubuntu based distribution which provides Plasma up to date. You have the choice between the standard, developer and unstable variants. It will likely cover your needs.