Apache 2.0 is not compatible with LGPLv2.1 is the reason back in 2014 and QT has continued to grow during this time. http://blog.qt.io/blog/2014/08/20/adding-l

Apache 2.0 is not compatible with LGPLv2.1 is the reason back in 2014 and QT has continued to grow during this time. http://blog.qt.io/blog/2014/08/20/adding-lgpl-v3-to-qt/ http://blog.qt.io/blog/2014/08/20/adding-lgpl-v3-to-qt/ > We also consider locked-down consumer devices using the LGPL’ed version of Qt to be harmful for the Qt ecosystem. ... Because of this, we are now adding LGPL v3 as a licensing option to Qt 5.4 in addition to LGPL v2.1. All modules that are part of Qt 5.3 are currently released under LGPL v2.1, GPL v3 and the commercial license. Starting with Qt 5.4, they will be released under LGPL v2.1, LGPL v3 and the commercial license. ... In Qt 5.4, the new Qt WebEngine module will be released under LGPL v3 in the open source version and under a LGPLv2.1/commercial combination for Qt Enterprise customers. ... Adding LGPLv3 will also allow us to release a few other add-ons that Digia before intended to make available solely under the enterprise license. ... The first module, called Qt Canvas3D, will give us full WebGL support inside Qt Quick. ... The second module is a lightweight WebView module ... There is a final add-on that will get released under LGPL v3. This module will give native look and feel to the Qt Quick Controls on Android. This module can’t be released under LGPL v2.1, as it has to use code that is licensed under Apache 2.0, a license that is incompatible with LGPL v2.1, but compatible with LGPL v3.