g2o_viewer was unable to start (0xc000007b)

I built the g2o library on Windows 7 with

• Qt 5.6
• Eigen 3.3.4
• libQGLViewer-2.7.1.

Everything compiles fine, but on the first run of g2o_viewer the program complains about the missing QGLViewer2.dll. Therefore, I added it to the directory.

After the second start, I get the application error from the title...

One must add:

• Qt5Core.dll
• Qt5Gui.dll
• Qt5Widgets.dll
• Qt5Xml.dll