Have you run this locally on one of the CentOS 7 boxes with qna? In my environment, I have a CentOS 7 (7.5) box and the relevance you posted above returns successfully.
cat /etc/centos-release
CentOS Linux release 7.5.1804 (Core)
Q: unique values whose (it !="") of (it as string as trimmed string) of values “serial_number” of structures “system_information” of smbios
A: VMware-56 4d 29 b7 b9 89 ef 13-f4 04 f4 73 75 58 92 e1
Here’s an easy litmus test; if you get the same error just testing for the existence of DMI, it’s likely a UEFI machine or, if that particular issue has been resolved, it’s some other issue: