Introduction

The error AttributeError: module 'enum' has no attribute 'IntFlag' occurs when Python imports a third-party package named enum instead of the standard library's enum module. This typically happens because a pip-installed package called enum34 (a backport for Python 2) shadows the built-in enum module, or because a file named enum.py exists in your project directory. The fix is to uninstall enum34 and remove any local enum.py file.

The Error

import re  # or any module that uses enum internally

# AttributeError: module 'enum' has no attribute 'IntFlag'

IntFlag was added to the standard library enum module in Python 3.6. If Python finds a different enum module first (one that does not have IntFlag), this error occurs.

Fix 1: Uninstall enum34

The most common cause is having the enum34 package installed:

pip uninstall enum34

enum34 is a backport of the enum module for Python 2 and Python 3.3 or earlier. It should NOT be installed on Python 3.4+, as it shadows the built-in enum module which has more features (including IntFlag).

Check if enum34 is installed

1pip show enum34
2# If installed, it shows version info
3# If not installed, shows "WARNING: Package(s) not found: enum34"
4
5pip list | grep enum
6# Look for "enum34" in the output

Fix 2: Remove Local enum.py File

Check if you have a file named enum.py in your project or current directory:

1# Check for local enum.py
2ls enum.py
3ls enum.pyc
4
5# On Linux/macOS
6find . -name "enum.py" -not -path "*/lib/*"
7
8# Remove it (or rename it)
9mv enum.py my_enums.py

Also check for a compiled __pycache__/enum.cpython-*.pyc file and delete it:

find . -name "enum.cpython*" -delete

Fix 3: Check import Order

Verify which enum module Python is loading:

1import enum
2print(enum.__file__)
3
4# Expected (standard library):
5# /usr/lib/python3.6/enum.py
6# or
7# /usr/local/lib/python3.6/enum.py
8
9# Problem (third-party):
10# /usr/local/lib/python3.6/site-packages/enum/__init__.py
11# or
12# ./enum.py (local file)

If the path points to site-packages or your local directory, that is the wrong module.

Fix 4: Fix in Virtual Environment

1# Create a clean virtual environment
2python3 -m venv clean_env
3source clean_env/bin/activate  # Linux/macOS
4# or: clean_env\Scripts\activate  # Windows
5
6# Verify enum is from stdlib
7python -c "import enum; print(enum.__file__)"
8
9# Install your dependencies (without enum34)
10pip install -r requirements.txt

Fix 5: Remove enum34 from requirements.txt

Check your requirements.txt or setup.py for enum34:

1# requirements.txt — REMOVE this line:
2enum34==1.1.10
3
4# Or make it conditional (only install on Python < 3.4):
5# In setup.py:
6install_requires=[
7    'enum34; python_version < "3.4"',
8]

Some older packages list enum34 as a dependency. If removing it breaks another package, update that package to a newer version that does not require enum34.

Understanding Python's enum Module

1import enum
2
3# Flag (Python 3.6+)
4class Permission(enum.Flag):
5    READ = 1
6    WRITE = 2
7    EXECUTE = 4
8
9# IntFlag (Python 3.6+) — supports bitwise AND, OR with integers
10class FilePermission(enum.IntFlag):
11    READ = 4
12    WRITE = 2
13    EXECUTE = 1
14
15# Can combine with integers
16combined = FilePermission.READ | FilePermission.WRITE  # FilePermission.READ|WRITE
17print(int(combined))  # 6
18
19# IntEnum (Python 3.4+)
20class Priority(enum.IntEnum):
21    LOW = 1
22    MEDIUM = 2
23    HIGH = 3
24
25# Comparable with integers
26print(Priority.HIGH > 2)  # True

IntFlag extends Flag and int, allowing both flag-style combinations and integer comparisons. It was added in Python 3.6 and is not available in the enum34 backport.

Debugging Checklist

1# 1. Check Python version (must be 3.6+)
2python --version
3
4# 2. Check if enum34 is installed
5pip list | grep enum
6
7# 3. Check which enum module is loaded
8python -c "import enum; print(enum.__file__); print(dir(enum))"
9
10# 4. Check for local enum.py files
11find . -name "enum.py" 2>/dev/null
12
13# 5. Check sys.path for unexpected directories
14python -c "import sys; print('\n'.join(sys.path))"

Common Pitfalls

• Installing enum34 on Python 3.6+: enum34 overwrites the standard library's enum module with an older version that lacks IntFlag, Flag, and auto(). Never install enum34 on Python 3.4 or later.
• A dependency pulling in enum34: Some older packages declare enum34 as a dependency unconditionally. Check pip show <package> for your installed packages to find which one requires enum34, and update or replace it.
• Local enum.py or enum/ directory: Python searches the current directory before the standard library. A file named enum.py or a directory named enum/ in your project shadows the built-in module.
• Cached .pyc files: After removing a local enum.py, the compiled __pycache__/enum.cpython-*.pyc may still be loaded. Delete the __pycache__ directory or the specific .pyc file.
• Conda environments: In Conda, enum34 can be installed through Conda channels even on Python 3.6+. Use conda list | grep enum and conda remove enum34 to fix.

Summary

• Uninstall enum34 with pip uninstall enum34 — it shadows the standard library on Python 3.4+
• Remove any local enum.py file or enum/ directory from your project
• Check which enum module is loaded with import enum; print(enum.__file__)
• IntFlag is part of the standard library enum module since Python 3.6
• Remove enum34 from requirements.txt and use conditional dependencies if needed for backward compatibility