First of all: 422 error may be something normal in some cases. Let’s see. Error 422 means that there is a connection error, in most of the cases, because Poloniex has rejected the connection or the connection failed. As we said before, it’s something normal to get 422 errors from time to time.
This error could be a real problem if you are getting it very often. Most likely it means that your bot is doing too many request / second. In this case, error 422 could turn into error 429, which is not good at all. If you persist doing too many requests, the exchange may break your api. In that case you will always get 422 error, no matter what you do.
In conclusion, if you are getting a lot of 422 errors, first of all you need to stop the bot for a while, for example, ten minutes. Now, raise BOT_DELAY parameter to 20 at least (on Poloniex), and run the bot again. If you still get 422 errors constantly, most likely your api key is broken and you need to create a new one. This time set BOT_DELAY to 20 or 25 in order to avoid doing so many requests / second.