In the INSTALL.md , there is a small error.

[JackTesla]

the INSTALL.md : Install from PyPI If you do not need C++ extensions (more details are [here]): pip install basicsr

If you want to use C++ extensions in JIT mode without compiling them during installatoin (more details are [here]): pip install basicsr

In fact, it should be like this: If you want to use C++ extensions in JIT mode without compiling them during installatoin (more details are [here]):

BASICSR_EXT=True
pip install basicsr

I think this will be more specific and can help avoiding errors.