The error 'scan commands not supported by redis server' is usually caused when a Redis version that does not support the SCAN command is being used. The SCAN command is used to iterate over keys in a Redis database, and it was introduced in Redis version 2.8.0. If you are using an older version of Redis, this command will not be available, and attempts to use it will result in the aforementioned error message.
To resolve this error, you can do one of two things: upgrade your Redis server to a version that supports the SCAN command or use an alternative method to iterate over keys. Upgrading your Redis server should be straightforward, and you can find instructions on how to do so on the official Redis website.
If upgrading is not an option for you, an alternative way to iterate over keys is to use the KEYS command. However, it is important to note that the KEYS command can be very slow and resource-intensive, especially if you have a large number of keys in your Redis database. Another option is to use a library that abstracts away the details of iterating over keys, such as ioredis or redis-py. These libraries provide a higher-level interface to Redis and handle key iteration for you.