Error 429 on Gunbot is common, especially on Poloniex. But, what does it mean? Error 429 means that your IP has been temporary banned for doing too many requests per second. Before getting this error, you should have seen a lot of 422 errors before.
What to do if you see error 429? First of all, stop the bot. Your IP is banned, so there is no point on continue doing request that are being ignored. Also your api key could be broken if you persist. After 30 minutes you will be able to start the bot again. This time be sure to reduce the number of requests / second your bot is doing. In order to do this, set BOT_DELAY to 20, or even better, to 25, to assure it won’t happen again.