How to Fix: OSError: [Errno 22] Invalid argument (File Paths)

If you are coding on Windows, you have likely encountered the frustrating OSError [Errno 22] error when trying to read or write files. This error almost exclusively affects Windows users and can stop a script dead in its tracks.

The error usually looks like this: OSError: [Errno 22] Invalid argument: 'C:\Users\Name\new_folder\data.txt'.

# WRONG — \n and \U are escape characters, not folder separators
f = open("C:\Users\Name\new_folder\data.txt", "r")
# OSError: [Errno 22] Invalid argument

# FIX 1 — raw string: r"" tells Python to ignore all backslash meanings
f = open(r"C:\Users\Name\new_folder\data.txt", "r")

# FIX 2 — double backslash: escape the escape character
f = open("C:\\Users\\Name\\new_folder\\data.txt", "r")

# FIX 3 — forward slashes: works on Windows, Mac, and Linux (recommended)
f = open("C:/Users/Name/new_folder/data.txt", "r")

# FIX 4 — pathlib: cross-platform, no backslash issues ever
from pathlib import Path
f = Path("C:/Users/Name/new_folder/data.txt").read_text()

The Cause: The Backslash \

In Windows, file paths use backslashes: C:\Users\Name\Documents\file.txt. In Python strings, a backslash is a “escape character”. It’s used for special things like \n (new line) or \t (tab).

If your username starts with a ‘U’ or ‘N’ or ‘T’, Python might misinterpret your file path as containing special characters instead of just a folder name.

Problem Code:

# Python sees "\new_folder" as a NEW LINE character + ew_folder
f = open("C:\Users\Name\new_folder\data.txt", "r")
# CRASH! OSError: [Errno 22] Invalid argument

The Fixes (Pick One)

Fix 1: Use Raw Strings (r"")

Put an r before your string. This tells Python “ignore all special backslash meanings.”

f = open(r"C:\Users\Name\new_folder\data.txt", "r")

Fix 2: Use Double Backslashes \\

Escape the escape character.

f = open("C:\\Users\\Name\\new_folder\\data.txt", "r")

Fix 3: Use Forward Slashes / (Recommended)

Python on Windows is smart enough to understand forward slashes, just like Mac/Linux.

f = open("C:/Users/Name/new_folder/data.txt", "r")

This is the most cross-platform compatible way to write paths.

Conclusion

The OSError [Errno 22] is simply a misunderstanding between how Windows handles paths and how Python handles strings. By using raw strings, forward slashes, or the Pathlib module, you can ensure your file paths are read correctly every time.

If you are new to handling files, check out our guide on Working with JSON in Python for more tips.

OSError: [Errno 22] Invalid argument on Windows — The Backslash Rule and the One Fix That Never Breaks

OSError: [Errno 22] Invalid argument on Windows traces back to one character: the backslash.

Python treats \ as the start of an escape sequence. \n means newline. \t means tab. \U starts a Unicode escape. Copy a Windows path directly into a Python string and any folder name starting with n, t, r, U, or b silently corrupts the path before Python ever touches the filesystem.

Three quick fixes work — raw strings, double backslashes, forward slashes. All three stop the crash. Forward slashes are the most portable: Python on Windows accepts them without complaint, and the same path string runs unchanged on Mac and Linux.

The permanent fix for any serious project is pathlib.

from pathlib import Path

data_file = Path(“C:/Users/Name/new_folder/data.txt”)
content = data_file.read_text()

Path objects handle separators automatically regardless of operating system, support method chaining for building paths safely, and integrate directly with open(), pandas.read_csv(), and every other file-handling function in the standard library.

Stop writing path strings by hand. Build every file path with Path() and this error disappears permanently — across Windows, Mac, and Linux, on every machine your code runs on.