# How to fix ImportError: cannot import name 'safe_str_cmp' from 'werkzeug.security'

Werkzeug 2.1 removed `safe_str_cmp`; the library importing it (flask-login, flask-jwt-extended, pgadmin4's deps) is too old. Upgrade that library (`pip install -U flask-login` etc.). Stopgap: `pip install "werkzeug<2.1"`, but that just postpones the upgrade.

## The exact error

```text
ImportError: cannot import name 'safe_str_cmp' from 'werkzeug.security'
```

## Fix it

1. Find the importer from the traceback (e.g. flask_login/utils.py).
   Expected: you know which package is stale

2. `pip install -U [that package]` (flask-login>=0.6.2 fixed it).
   Expected: it uses hmac.compare_digest now

3. Re-run your app.
   Expected: no ImportError

## When this applies

werkzeug>=2.1 and an old flask extension imports safe_str_cmp

## When this does NOT apply

your own code (use hmac.compare_digest directly)

## Versions

werkzeug >= 2.1 with old flask extensions

## Why it happens

Werkzeug removed the helper; its own docs point at hmac.compare_digest.

## Edge cases

Pinning werkzeug[2.1 can conflict with Flask]=2.2 requirements; upgrade the extension instead.