If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the LRANGE command, it’s probably because you’re passing a key with the wrong data type.

To fix this issue, be sure that the key you pass to the LRANGE command holds a list.

Example of Error

Here’s an example of code that causes the error:

LRANGE countries 0 -1

Result:

(error) WRONGTYPE Operation against a key holding the wrong kind of value

Here the countries key contains a set and so we get an error.

We can use the TYPE command to check the key’s data type:

TYPE countries

Result:

set

As suspected, the key contains a set instead of a list.

Solution

The solution is to make sure the key we pass contains the correct data type. The LRANGE command is designed to be used with lists, so we should make sure the specified key contains a list.

Here’s an example of running the command against a key that holds a list:

LRANGE animals 0 -1

Result:

1) "Dog"
2) "Cat"
3) "Bird"

This time we didn’t get the error because the animals key holds a list.

Let’s verify the data type with the TYPE command:

TYPE animals

Result:

list

A list as expected.