I am trying to bundle a PyQt project using Pyinstaller. I tried creating package using command pyinstaller --onedir Hello.py.
This creates dist folder and has Hello.exe. On running it gets the error: This application failed to start because it could not find or load the Qt platform plugin "windows"in "".
Reinstalling the application may fix this problem.
I solved the issue in my PC by

setting environment variable QT_QPA_PLATFORM_PLUGIN_PATH

or by 

Copying dist\Hello\PyQt5\Qt\plugins\platform folder to where Hello.exe exists.

But this issue exists when I bundle to a single file using command --onefile, and run on any other machine, where QT_QPA_PLATFORM_PLUGIN_PATH is not set.
Can someone help to figure out the issue.
If you using python 3.4 and pip refuses to install pyqt5

Download and install
Pyqt5 manually to %your python 3.4 dir%
Create directory
Go to %your python 3.4 dir%\Lib\site-packages\PyQt5 create directory Qt and then move plugins folder there.
Add plugins
Then you can add ('C:/Python34-32/Lib/site-packages/PyQt5/Qt/plugins', 'PyQt5/Qt/plugins') to data in your spec file.

be sure to download PyQt 5.4.1 or other version that supports python 3.4

At least that solved my problem. I hope this will help somebody
Error: Could not find or load the Qt platform plugin "windows" - PyQt + Pyinstaller