I updated my TechTools 10l to the latest version a few days ago, which said it had fixed the error rebuilding problem. I just tried to do a volume rebuild on my external WD drive and got this error for the first time. Any advice? Thanks.
MacBook Pro 17" 2011 - OS10.13.6 - TechTools Pro Version 10.1.1 (4359-0578e64)
MacBook Pro 17" 2011 - OS10.13.6 - TechTools Pro Version 10.1.1 (4359-0578e64)