unsuitable Qt version “” from NOTFOUND, this code requires qt 4.x

[gamaliel]

I have old software that has to use an old version of openCV that requires qt4x. I installed qt4.8.4. I did not get any error messages. However when I attempt to install opencv I get the message unsuitable Qt version “” from NOTFOUND, this code requires qt 4.x. I am using Ubuntu 12.04

[jsulm]

@gamaliel How do you install opencv and how did you install Qt 4.8.4? Do you use Ubuntu packages for both?

[gamaliel]

I couldn't find an ubuntu package for qt4.8.4. The file I downloaded is qt-everywhere-opensource-src-4.8.4.tar.gz. The URL I downloaded from is https://download.qt.io/archive/qt/4.8/4.8.4/. I ran qmake -v and although it says qmake is version 2, qt is 4x

[SGaist]

Hi,

You downloaded the sources of Qt.

You have to build it first. Therefore, you should also rather download the 4.8.7 release as it is the latest and last version of the Qt 4 series.

[jsulm]

@gamaliel My Ubuntu 18.04 has Qt 4.8.7 packages like libqt4-dev, so you should be able to install Qt 4 easily.