Sometimes Api keys can stop working and we need to create a new one, but in what situations an Api key can get broken? Mainly there are 4 causes:
1- You did too many request / second and the exchange removed your api key.
2- You disabled 2FA at Bittrex and when you do it, all api keys are removed.
3- You connected to the api key from 2 different devices / apps at the same time. If you do, the api key could get broken.
4- You connected to the api key from 2 different devices with different time zone. Exchanges usually have some kind of protection, so if you connect from a device at 6 pm and after that you connect from other device with different time zone at 4 pm, they break your api key. Note that they won’t break your api if you connect at a later time than the first connection.