It is difficult to troubleshoot an error based on an error message. The best way to get this issue addressed is to contact the learning support staff by opening a ticket at below link
https://access.redhat.com/support/cases/#/case/new
Please include below details in the ticket
1) exact chapter and section
2) Command you have tried and the screenshot of the error message
3) Any other details that you think may be necessary to troubleshoot this issue.
Thanks,
Jayadev
Red Hat
Learning Community
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