Jedis: ERR wrong number of arguments for ‘rpush’ command

While refactoring a large project with some legacy unmanageable code which used Redis, I came across this exception:

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Exception in thread "main" redis.clients.jedis.exceptions.JedisDataException: ERR wrong number of arguments for 'rpush' command
    at redis.clients.jedis.Protocol.processError(Protocol.java:59)
    at redis.clients.jedis.Protocol.process(Protocol.java:66)
    at redis.clients.jedis.Protocol.read(Protocol.java:131)
    at redis.clients.jedis.Connection.getIntegerReply(Connection.java:188)
    at redis.clients.jedis.Jedis.rpush(Jedis.java:873)
    at com.caffinc.RedisCacheManager.storeDoubleList(RedisCacheManager.java:276)

It was intermittent and used to appear only sometimes, and used to mess up the process. After pulling my hair out for a while, I discovered that passing an empty list to jCon.rpush( name, values ); causes this exception. Rather weird if you ask me. Empty lists are completely logical, and in most cases necessary. I handled this by simply checking if the list was empty before inserting into Redis.

I thought this would be all, as the problem did disappear for a while. But when I checked in my code after making some major refactoring, the problem returned! Try as I might, it this call kept failing and everything seemed fine on my machine locally…

I realized I’d upgraded Redis on my machine, and also Jedis in my code. I upgraded Redis from 2.2 on the server to 3.0.2 and things were working fine again!