Per your other thread, indeed your Redis instance crashed. This was a post-crash error message that occurred because XenForo tried to read from Redis after Redis was already gone. In the case of this specific error message at least, it is a coincidence that the cache entry being requested has a key name that starts with 'vw_'; that just happened to be the next value requested after the crash.
Your Redis logs will be more useful to you here, and since a crash was involved, you will probably need to talk to Redis developers and provide them with a backtrace from the crash. Then they will be able to give you more information about what caused it, and they will also be able to patch Redis so that it doesn't crash in that situation again.