# WRONGTYPE Operation against a key holding the wrong kind of value

**Code:** `WRONGTYPE` · **Category:** Node.js · **Seen on:** Node.js

A Redis command was used on a key of a different type (e.g. HGET on a string key).

## Meaning

Each Redis key has one type (string, hash, list, set, zset). Reusing key names across features or changing data shape causes it.

## Common causes

- Same key name used for different data types
- Data migrated without clearing old keys
- Bug writing the wrong type

## Quick fix

1. Check the key type: TYPE key
2. Use namespaced key names (user:42:profile)
3. Delete/migrate the old key

## Detailed fix by platform

### Linux

1. `redis-cli TYPE session:42`

## How to diagnose

1. **Key** — Which key and command?
2. **Type** — TYPE key result

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Source: [WhatIsMyError](https://whatismyerror.com/errors/nodejs/redis-wrongtype)