Recently I Successfully upgraded Tableau Server from 10.2.0 to 10.3.0.
After Tableau Server upgradation to 10.3, I'm getting file store status unavailable on the Primary node and the status of the primary node is degraded. Attached screenshots helped you to understand the issue.
Following images help you to understand the issue.
Please let me know if you need any further information.
Thanks & Regards,
Please take a look at this recent article, which I think refers to your issue
All the best