UnRAID Server requested an update to 6.9.0 RC1 via it's banner.
After the reboot, the array will not start because it says it is unlicensed. Provides the following message:
The following excerpt from the log file seems relevant.
There isn't an obvious retrieve key function within the UnRAID web site, so this post accompanies a support request email.
Will post any fixes found here as this is presumably a known or reoccurring problem for others.