It could be due to several reasons:
1. Withdrawal services may be unavailable temporarily due to maintenance. Hashnest from time to time will do a wallet maintenance. After the maintenance, you will be allowed to make a withdrawal.
2. If your balance is below 0.001 BTC, or if you do not meet the minimum withdrawal amount, you will not be able to make any withdrawal. Always ensure that your balance amount is sufficient before making any withdrawal.
You may wish to check what is the minimum and maximum withdrawal limit?
3. If your balance is sufficient but still unable to make any withdrawal, it could be due to incorrect wallet address. Confirm that your wallet address is valid before you withdraw. Make sure you are using the right wallet for the right coin!
4. 2FA failure. If you failed to verify your account with 2FA, you cannot withdraw. Follow the instructions here if you find that your phone, Google authenticator or 2FA is not working.
5. Your account security was compromised and Hashnest locked your account to prevent unauthorised withdrawals. Please contact us ASAP.
If you had try to resolve the issue by following the steps above but still receive an error message from us, contact us immediately for assistance.