Hi @grif , and welcome to the forum!
The issue you’re seeing looks like a recently fixed bug in our testing channel; Rockstor version 5.0.11-0 and later include this fix:
I presume you have installed the ISO available on our download page (Leap 15.6 base OS recommended) so you should be able to activate the Testing channel (https://rockstor.com/docs/interface/system/update_channels.html#testing-channel) and the update Rockstor to the latest version (5.0.12-0). You should then no longer see this error.
This testing channel release is very close to making it as our next stable release so you can switch to the stable channel after that if you prefer.
Let us know how it goes or if you’d like more details on any of the above.