What is the wrong type of operation?
A wrong type of operation is an operation against a key holding the wrong value. For example, trying to increment a string value or decrement an integer value. Redis will report such operations as errors.
Why does it happen?
There are a few reasons why this might happen:
- You are trying to operate on a key that is not of the correct type. For example, you might try to increment a string value or append to a list that isn’t initialized.
- You are using the wrong type of value for the operation. For example, you might try to use a list as a key in a dict or you might try to perform set operations (union, intersection, etc.) on values that are not sets.
- The data type for the key or value has changed and is no longer compatible with the operation you are trying to perform. This can happen when upgrading Redis or when changing the COMPRESSION setting.
To avoid this error, make sure that you are using the correct data type for the operation you are trying to perform.
How to fix a wrongtype operation?
If you receive the error message “wrongtype operation against a key holding the wrong kind of value” in Redis, it means that you are trying to perform an operation on a data type that it cannot be performed on.
For example, you might be trying to increment an integer value using the INCR command, but if the key is actually set to a string value, you will receive this error.
To fix this, you will need to either convert the value to the correct data type or delete the key and start over.