ERR wrong number of arguments for command: Wrong number of arguments for command

What does it mean?

A Redis command was sent with fewer or more arguments than expected. The command was rejected without being processed because its syntax was not satisfied.

Why does it happen?

Missing/extra parameters (e.g., just SET key instead of SET key value); variables passed as empty/undefined; the command called with the wrong argument order; or faulty array/argument expansion (spread) in the client library. Common with dynamically built commands.

How to fix it

Check the command's correct signature (e.g., SET key value [options]); consult the official command reference. In client code, verify that arguments (especially those coming from arrays) are not empty/missing. If you build commands from user input, validate the argument count beforehand. Try the command manually in redis-cli to confirm the expected number of arguments.