matplotlib and pyinstaller

[Ezra Savitz]

I am trying to use pyinstaller to create an exe file for my application. I had been using it no problem for a couple weeks (with matplotlib) until today when I keep getting the following error: 

assert mpl_data_dir, "Failed to determine matplotlib's data directory!"

AssertionError: Failed to determine matplotlib's data directory!

I've looked all over the internet for solutions but none of them work for me. I was hoping someone could help me out.

Please let me know if you have any solution, thanks!