EC
IsADirectoryError
PythonERRORCriticalI/O ErrorHIGH confidence

Operation expected a file, but got a directory

What this means

A subclass of `OSError`, raised when a file operation (like `open()` or `os.remove()`) is requested on a directory. These operations are only valid for files.

Why it happens
  1. 1Trying to `open()` and read from a path that points to a directory.
  2. 2Attempting to delete a directory using `os.remove()` instead of `os.rmdir()`.
  3. 3Passing a directory path to a function that expects a file path.
How to reproduce

This error is triggered by attempting to open a directory for reading as if it were a file.

trigger — this will error
trigger — this will error
import os
# Create a directory to demonstrate
if not os.path.exists("my_test_dir"):
    os.mkdir("my_test_dir")

try:
    with open("my_test_dir", "r") as f: # Trying to open a directory
        content = f.read()
except IsADirectoryError as e:
    print(f"Caught IsADirectoryError: {e}")
finally:
    os.rmdir("my_test_dir") # Clean up

expected output

Caught IsADirectoryError: [Errno 21] Is a directory: 'my_test_dir'

Fix 1

Check if the path is a file before opening

WHEN A given path could be either a file or a directory.

Check if the path is a file before opening
import os
path = "some_path" # Could be a file or a directory
if os.path.isfile(path):
    with open(path, "r") as f:
        # process file
        pass
elif os.path.isdir(path):
    print(f"{path} is a directory, not a file.")

Why this works

`os.path.isfile()` specifically checks if the path points to a file, allowing you to avoid attempting file operations on directories.

Fix 2

Use the correct function for directories

WHEN You need to perform an operation on a directory, such as deleting it.

Use the correct function for directories
import os
import shutil

dir_path = "my_empty_dir"
if os.path.exists(dir_path):
    # os.remove(dir_path) # -> Would raise IsADirectoryError
    os.rmdir(dir_path)   # Correct for empty directories

non_empty_dir = "my_non_empty_dir"
if os.path.exists(non_empty_dir):
    shutil.rmtree(non_empty_dir) # Correct for non-empty directories

Why this works

Python's `os` and `shutil` modules provide separate functions for file operations (`os.remove`) and directory operations (`os.rmdir`, `shutil.rmtree`). Using the correct function for the target object type is essential.

Code examples
Triggerpython
with open("/etc") as f:
    pass  # IsADirectoryError: Is a directory
Handle with try/exceptpython
try:
    with open(path) as f:
        data = f.read()
except IsADirectoryError:
    print(f"{path} is a directory, not a file")
Avoid with isfile() checkpython
import os
if os.path.isfile(path):
    with open(path) as f:
        data = f.read()
What not to do

✕ Catching `IsADirectoryError` and just ignoring it

This error points to a fundamental misunderstanding in your code about what it's operating on. Ignoring it means your program is failing to process the data it was supposed to.

Version notes

Sources
Official documentation ↗

cpython/Objects/exceptions.c

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