For users who withdraw to Coinbase using the free direct withdrawal process, there has been an increased number of 'rejected' free withdrawals from the Coinbase side, and we are waiting for a response from Coinbase. 

This is not a rate limit issue, but simply an 'unknown error' on Coinbase side. We are currently waiting on a fix from them, and since this is affecting many of our users, we have suspended the free withdrawals (only) for 48 hours.

We advise anyone who has experienced this issue to contact Coinbase support directly, as only they can assist you.

You can still transfer to Coinbase in a regular withdrawal, and the fees are extremely low at this point (about 4 cents for BTC). To do this, you just need to add your Coinbase wallet address to 'withdrawal addresses' in your account settings, and make the withdrawal to there.

UPDATE: The free withdrawals are working again since 12pm CET on 15th September. You may still encounter this 'unknown rejected' error, as this has been affecting users for a while. If so please contact Coinbase Support.

Thank you for understanding,
Your NiceHash team