Every Python-related executable broken: "Fatal Python error: init_import_size: Failed to import the site module"

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I'm very new to python and especially to its ecosystem. Today, I was trying to invoke a python command from my command line that worked perfectly yesterday, but today I got the following fatal error:

Fatal Python error: init_import_size: Failed to import the site module
Python runtime state: initialized
ModuleNotFoundError: No module named 'site'

Current thread 0x00000cac (most recent call first):
<no Python frame>

While trying to find the problem, I soon realized that it was not special to my command. In fact, all python-related executables produce the same error when invoked from any command prompt, no matter where I am in my filesystem. python, python3, anaconda (and its prompt), conda, pip, pip3, ... All of these suddenly don't work anymore. They all fail with the same error message, only the thread is altering.

In my research I found a very similar error very often, but it was about the encodings module. Also I haven't read about issues where the entire python ecosystem just broke.

Solutions to said similar error seem to include doing something with the PYTHONPATH and PYTHONHOME envs if they exist. But I don't have them, neither as user variable nor as system var.

I installed python by installing anaconda3 via scoop. It should be the latest version (2020.11). I've been using the installation inside of PyCharm as well as via the command line.

Does anyone know what the problem here could be? I'm kinda stuck here because I can't even use conda or pip for diagnostics, like calling conda list to find out more about the site packages' status. So, if anyone could help me with this, I'd be very thankful!

conda pip python
5 Answers

I had this error.

For me, I had some project tree (fictitious):

doc/
├── project/
│   ├── embedded/
|   |   ├── __init__.py
│   │   ├── deep_file
│   │   └── utils/
│   │       └── os.py # < This one! Look here!!
│   │       └── deep/
│   │           └── folder/
│   │               └── very_deep_file
│   └── less_deep_file
|...

Within this tree, I had a file named .../utils/os.py.

Pycharm debug mode would find this os.py and use it in place of the default os.py. To solve this problem, I renamed os.py to something else.

What a dummy I am! Hopefully this saves other people time and headache!!

user_3608260

I had the same error when I had a python file called stat.py in the working directory. After deleting it, everything returned to normal.

user_183920340

I had a similar problem that I cannot use any command in the anaconda Scripts folder. The anaconda new install was using Python 3.8 while I had system variable PYTHONPATH set up for the paths for Python 3.9. My solution was to delete the PYTHONPATH system variable, and the anaconda navigator worked again.

user_43385270

The thing happened to me too. It fixed automatically when I first ran it without importing the modules and then added modules and ran again. For me it was the time module

user_165116180 
executing python from command prompt failed with very same error (which was working fine earlier).
Fatal Python error: init_import_site: Failed to import the site module
Python runtime state: initialized
Traceback (most recent call last):
  File "C:\.......\Python\Python310\lib\site.py", line 73, in <module>
    import os
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 879, in exec_module
  File "<frozen importlib._bootstrap_external>", line 1012, in get_code
  File "<frozen importlib._bootstrap_external>", line 672, in _compile_bytecode
ValueError: bad marshal data (unknown type code)

However after restarting my windows machine, i didn't get this error.
user_192876200
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