I did not compile Qt myself, rather I used installer from official Qt website (5.6 beta is available since few days ago). Installation was successful, Qt folder conatins bin folder with qmake and everything. Building apps in Qt Creator works.
However, when I try to launch Qt using VS addin 1.2.5.9 I get error
No default Qt version found. Pleae check your Qt Visual Studio Add-in settings.
I have edited QT5 -> Qt Options to contain the correct Qt path to 5.6 beta, error still persists.
I have also added QTDIR into Path in Windows 10.
I am using Community Edition of Visual Studio 2015
How to fix this? Create new Qt project under VS fails as well.
The Qt Visual Studio add-in is no longer supported in Visual Studio 2015. Microsoft decided to deprecate AddIn support in Visual Studio 2013 and with Visual Studio 2015 all support for it has been removed. This is covered in https://bugreports.qt.io/browse/QTVSADDINBUG-404. However, there's an extension called Qt5Package you can install instead.
I found when I tried to add Qt 5.6.0 Beta in the extension I got the error "This Qt version uses an unsupported makefile generator (used: MSVC.NETMSBUILD, supported: MSVC.NET, MSBUILD)". The workaround is in C:\Qt\Qt5.6.0\5.6\msvc2015\mkspecs\common\msvc-desktop.conf Qt 5.6.0 splits all the version-specific changes into a separate file msvc-base.conf. If you copy the contents of this file and replace the line "include(msvc- base.conf)" in mscv-desktop.conf then Qt5Package recognises the Qt 5.6.0 Beta with no problems.
Note this still needs to be fixed in Qt5Package.
来源：https://stackoverflow.com/questions/34170448/how-to-fix-qt-vs-add-in-for-qt-5-6-beta-and-vs2015