if you want to open your wallet using private key i think it will be good if you use mycrypto.com
because mycrypto is a team from the people that left MEW
i didnt knew this facts but thanks for letting me know . i heard mycrypto before and a couple of people already suggested it but i didnt thought that it was a good site since the team are are mew's ex employee . still using a private key is risky no matter what site your using not just mew , that is why experts always advice to use metamask as an alternative to private keys . about the error i also think that its because of the low fee as i also encountered it before .