Password Reset Token Issues in Django

Based on your description of users receiving "Invalid Token" errors during password resets, there are several potential causes to investigate:

Possible Causes

1. Token Expiration: By default, Django password reset tokens expire after a certain period (typically 3 days). If users are clicking links in older emails, they'll receive invalid token errors.

2. Email Client Issues: Mobile email clients might be pre-fetching links, which can invalidate tokens before users actually click them.

3. Multiple Reset Requests: If users request multiple password resets, only the most recent token will be valid. Previous tokens become invalid.

4. URL Truncation: Some email clients or messaging apps might truncate long URLs, breaking the token.

5. Security Vulnerability Patches: Django has had security issues with password reset tokens in the past (like CVE-2019-19844), and your version might be affected by similar issues.

Diagnostic Steps

1. Logging: Add detailed logging around the password reset process to capture when and why tokens are being rejected.

PYTHONCopied
# Add to your settings.py
LOGGING = {
    'version': 1,
    'handlers': {
        'file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': 'password_reset_debug.log',
        },
    },
    'loggers': {
        'django.contrib.auth': {
            'handlers': ['file'],
            'level': 'DEBUG',
            'propagate': True,
        },
    },
}

2. Extend Token Validity: You could temporarily extend the token validity period to see if that resolves the issue.

PYTHONCopied
# In settings.py
PASSWORD_RESET_TIMEOUT = 60 * 60 * 24 * 7  # 7 days in seconds instead of default 3 days

3. Check for Mobile-Specific Issues: Since 80% of your users are on mobile, test the reset process thoroughly on various mobile devices and email clients.

4. Monitor User Behavior: Track how long users typically take between requesting a reset and clicking the link.

5. Consider Custom Implementation: If needed, you might need to implement a custom password reset view that's more resilient to your specific use cases.

If you continue experiencing issues, consider upgrading to a newer Django version as security patches and improvements to the authentication system are regularly released.