This means you ran a command meant for one data type against a key that holds a different type. Using the right command for the key's actual type resolves it. Jump to your situation below or work through the methods in order.
The Redis WRONGTYPE Operation against a key holding the wrong kind of value error means a command was run against a key whose data type does not match the command. Redis keys each hold a specific type, string, hash, list, set, sorted set, stream, and commands are type-specific: running HSET on a key that holds a plain string, or LPUSH on a hash, triggers WRONGTYPE. It usually comes from a key-name collision (two parts of the code using the same key for different structures) or a wrong assumption about a key's type. The fix is to check the actual type with TYPE key, then either use the correct command for that type or use a different key name so each structure has its own key. Namespacing keys by type prevents collisions.
Every Redis key has one data type, fixed when the key is created. Commands belong to a type too, so HSET expects a hash and LPUSH expects a list. WRONGTYPE means the command and the key's type disagree: the key exists, but it is not the kind the command operates on.
The usual root cause is a naming clash, two code paths reusing the same key for different structures, or code assuming a type the key does not actually have. Checking the type tells you the truth, and either using the right command or giving each structure a distinct, namespaced key resolves it.
“WRONGTYPE is Redis saying that key is not the shape you think it is. The key exists, but you fired a hash command at a string, or a list command at a set. Almost always it is a key-name collision, two bits of code grabbing the same key for different data. So I run TYPE on the key to see what it actually is, then either use the right command or, better, namespace the keys so a session string and a user hash never share a name. Clear naming makes this error vanish.”
TYPE mykey
user:100:profile (hash) and user:100:sessions (list).DEL mykey
WRONGTYPE means the command does not match the key's data type, usually a key-name collision. Run TYPE key to see what it actually holds, then use the matching command or give each structure a distinct, namespaced key name. Recreate a key with DEL if it must change type.
If WRONGTYPE appears intermittently, two services are likely writing the same key as different types under load; logging which client and command set the key, or using a key-naming convention enforced in code review, isolates the offender. You can also submit your error to us for a tailored fix.