ERR Unknown option or number of arguments for CONFIG SET: Unknown option or number of arguments for CONFIG SET (older versions: Unsupported CONFIG parameter)

What does it mean?

The configuration parameter you tried to change with CONFIG SET is not recognized in this Redis version, or the number of arguments is wrong. In Redis 7 the full message is "ERR Unknown option or number of arguments for CONFIG SET - '<name>'"; older versions return "ERR Unsupported CONFIG parameter". CONFIG GET does not raise an error for an unknown parameter; it returns an empty list.

Why does it happen?

A misspelled parameter name; using a parameter from a different Redis version (parameters can be added and removed between versions); or the managed cloud service not allowing certain parameters to be changed. Running old scripts on newer/older versions is the typical cause.

How to fix it

Verify the valid parameter name. List current settings with a pattern, such as CONFIG GET 'maxmemory*'. Check the parameter list in the documentation for your Redis version; see the version with INFO server. If restricted on a cloud service, use the parameter set the provider allows. Update your scripts for the target version.