Receiving the message you received is common. But, I have not seen a definitive solution for it. I suggest you use my search link in trying to solve your problem: unknown error apple. You will see a number of links that are, or may be, related to your specific problem.
And, if you want to contact Apple Support to deal with your problem, see:
Get a call from Apple support to help solve your problem using this
link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362
Apple ID Support https://support.apple.com/apple-id
Apple Support Twitter https://twitter.com/AppleSupport
Apple ID account security for country-specific and
region-specific help https://support.apple.com/en-us/HT204169
Get Support: We’re here to help https://getsupport.apple.com/. Go through
the options to find the best one.. You will see a number of links that are, or may be, related to your specific problem.