PyCharm shows unresolved references error for valid code

File | Invalidate Caches... and restarting PyCharm helps.

Dmitry's response didn't work for me.

I got mine working by going to Project Interpreters, Selecting the "Paths" tab, and hitting the refresh button in that submenu. It auto-populated with something called "python-skeletons".

edit: screenshot using PyCharm 3.4.1 (it's quite well hidden)

There are many solutions to this, some more convenient than others, and they don't always work.

Here's all you can try, going from 'quick' to 'annoying':

• Do File -> Invalidate Caches / Restart and restart PyCharm.
  • You could also do this after any of the below methods, just to be sure.
• First, check which interpreter you're running: Run -> Edit Configurations -> Configuration -> Python Interpreter.
• Refresh the paths of your interpreter:
  • File -> Settings
  • Project: [name] -> Project Interpreter -> 'Project Interpreter': Gear icon -> More...
  • Click the 'Show paths' button (bottom one)
  • Click the 'Refresh' button (bottom one)
• Remove the interpreter and add it again:
  • File -> Settings
  • Project: [name] -> Project Interpreter -> 'Project Interpreter': Gear icon -> More...
  • Click the 'Remove' button
  • Click the 'Add' button and re-add your interpeter
• Delete your project preferences
  • Delete your project's .idea folder
  • Close and re-open PyCharm
  • Open your project from scratch
• Delete your PyCharm user preferences (but back them up first).
  • ~/.PyCharm50 on Mac
  • %homepath%/.PyCharm50 on Windows
• Switch to another interpreter, then back again to the one you want.
• Create a new virtual environment, and switch to that environments' interpreter.
• Create a new virtual environment in a new location, and switch to that environment's interpreter.
• Switch to another interpreter altogether; don't switch back.

If you are using Docker, take note:

• Make sure you are using pip3 not pip, especially with remote docker and docker-compose interpreters.
• Avoid influencing PYTHONPATH. More info here: https://intellij-support.jetbrains.com/hc/en-us/community/posts/115000058690-Module-not-found-in-PyCharm-but-externally-in-Python .