[SOLVED] pip: 'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers

pip: 'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers

I tried running pip install gym==0.21.0

but got the cryptic error:

Collecting gym==0.21.0
  Using cached gym-0.21.0.tar.gz (1.5 MB)
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error
  
  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [1 lines of output]
      error in gym setup command: 'extras_require' must be a dictionary whose values are strings or lists of strings containing valid project/version requirement specifiers.
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

What may be causing this error?

Solution

Based on the comments in the issue section at https://github.com/openai, these are the changes that need to be made -

pip install setuptools==65.5.0 pip==21 # gym 0.21 installation is broken with more recent versions
pip install wheel==0.38.0

I was facing the same issue and after doing the above, it was resolved.

The problem has been addressed here and here.