Operation against a key holding the wrong kind of value
This error occurs when a client attempts to execute a command on a key that holds a value of an incompatible data type. Redis is strictly typed, and commands are specific to data structures.
- 1Using a string command (e.g., GET) on a key that holds a List.
- 2Using a Hash command (e.g., HGET) on a key that holds a Set.
- 3Application logic not validating or tracking key types before operating on them.
A client runs GET on a key that stores a Redis List instead of a String.
SET mykey "hello" DEL mykey RPUSH mykey "a" "b" "c" GET mykey
expected output
(error) WRONGTYPE Operation against a key holding the wrong kind of value
Fix 1
Check the key type before operating on it
WHEN When you are unsure what type a key holds
TYPE mykey # returns: list # then use list commands LRANGE mykey 0 -1
Why this works
The TYPE command returns the data type of the value stored at a key, allowing you to choose the correct command.
Fix 2
Delete and recreate the key with the correct type
WHEN When the key was created with the wrong type by mistake
DEL mykey SET mykey "correct string value"
Why this works
Deleting the key removes the existing value, then SET creates a new String value.
✕ Ignore the WRONGTYPE error and retry with a different command
Blindly retrying corrupts application logic; investigate why the wrong type exists.
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