Poloniex

Insufficient balance for the requested action. Mind the exchange fee.

Original error code: poloniex.insufficient_funds

If you get an error showing that your balance is insufficient, it can be based on the following reasons: 

1. The amount placed in your order is less than the minimum trading amount allowed on Poloniex. 

2. The amount of your order exceeds the available balance. 
This can happen in rare cases if something has gone wrong in the TabTrader's prevention mechanism that immediately indicates on the amount being greater than the available balance before the order confirmation.

3. Exchange fees have not been included in the order total, which means that the order consisted of the entire available balance.

The API key has invalid values. Please, check if the spelling is correct. Or create a new API.

Original error code: poloniex.400.bad_request

This is a common issue you can have when adding your new API keys. 
The most typical case is that your API public key (in the upper field) has the wrong values in it: not the ones your exchange exposed once the keys were generated. 
It can happen due to an accidental typo or copying some other value by mistake. 

However, this error message can also mean that these API keys no longer exist. 
It can happen because of the keys have been expired or simply removed from your exchange account. 
Make sure your API is still active in your API management settings on your exchange account. 

The API keys are not authorized on the exchange. Create a new API.

Original error code: poloniex.401.unauthorized

This error usually happens for two general reasons: 

1. The API with such values is not found on the exchange. This may happen due to the wrong signature. 
Check the spelling of your secret key.  

2. The API keys have been expired, so you need to create a new API.