An error occurred, please try again or try an alternate form of payment

I have WooCommerce Authorize.Net Gateway By SkyVerge. Recently, I’m getting this error at checkout: “An error occurred, please try again or try an alternate form of payment”

I have tested the checkout & it seems this error happens randomly; it works not but not in few hours. I de-reactivated the plugin a few times creating new APIs & secret key but it was still the same. After reading a an article here I deactivated the Asset Optimization plugin Hummingbird Pro & later tests were all OK. However, I’m not confident this error is eliminated since the nature of the error is on & off.