I was having the same issues with Kraken. Numerous error messages preventing my trade to go through. I informed support and they responded with this:

Jen (Kraken Support)
Sep 2, 16:07
Hi!
We're aware of the kind of error you're seeing, it's a problem from when our system gets overloaded with traffic. We're in the process of adding capacity to deal with it, but in the meantime we ask your patience while placing trades.
Thanks for using Kraken,
Jen

Hopefully, this will be resolved soon. I have an account with Bittrex too. However, I plan on staying with Kraken. Maybe, one day, I 'll learn enough from Luc's videos that I'll start layering my orders in advance of panic drops that I spotted using his trading methodology. Can't wait.

Good luck with trading on Kraken, hope all works out well and you make a ton of money.