Attempting to open or process a file at a path that does not exist in the file system.
FileNotFoundError is raised when a file-related function (like open(), os.remove(), or os.listdir()) is called on a relative or absolute path that cannot be resolved to any existing file or directory.
Using incorrect relative paths that depend on the current working directory, typos in file names, or attempting to open a file before its parent directory is created.
1# Bug: Assuming data.txt is in the current directory, but CWD is different!2with open('data.txt', 'r') as f:3 content = f.read() # FileNotFoundError1import os2from pathlib import Path3 4# Fix 1: Resolve path relative to the script file location5SCRIPT_DIR = Path(__file__).resolve().parent6file_path = SCRIPT_DIR / 'data.txt'7 8# Fix 2: Check if file exists before opening9if file_path.exists():10 with open(file_path, 'r') as f:11 content = f.read()12else:13 print(f"File not found at: {file_path}")Simulate standard system builds to trigger compiler trace records and track memory crashes locally.
Python searches for 'data.txt' in the active operating system CWD. If the script was launched from a different folder, the relative path fails to resolve, throwing FileNotFoundError.