It is important to restrict PATH as described above. If you have Strawberry Perl and/or Mercurial installed, it will pick up gcc & openssl from the wrong places.
### Without Qt Creator
/c/Qt/Qt5.10.1/5.10.1/mingw53_32/bin/
If you are an Arch Linux user, refrain from updating system with `pacman -Syu`. Always update runtime separately as described on the home page, otherwise you might end up with DLLs incompatibility problems.