WRONGTYPE Operation against a key holding the wrong kind of value

The error arises when attempting a KV operation (set or get) in Vercel after creating an entry using a different data structure.

Replicating the error

await kv.set('userSession', '123abc');

Subsequently, we opt to change the data structure.

await kv.hset('userSession', { userId: 123, email: 'ex@example.com' });

Error:

UpstashError: WRONGTYPE Operation against a key holding the wrong kind of value, command was: ["hset","userSession", ...]

Solution

Remove the key from Vercel before modifying the data structure.

1. Go to Vercel: https://vercel.com/dashboard/stores/kv
2. Delete that key:

DEL userSession