I am following the “Qubes builder” instructions. The only reference to this error is on a github issue only referring to the error as an example for properly verbose errors. Which is kind of ironic because I am not entirely certain how to go about solving this problem.
When DispVM fails to start in Qubes 4.1, there should be a notification about it. In Qubes 4.0 not all the cases had notification. In any case, you can check journalctl in dom0 for more details about it.
Mar 14 18:24:30 dom0 qrexec-policy-daemon[2455]: qrexec: qubes.VMShell+WaitForSession: builder1 -> @dispvm: denied: policy define 'allow' action to @dispvm at /etc/qubes/policy.d/90-default.policy:94 but no DispVM base is set for this VM
But how do I set a base for the VM. I have a debian and a whonix disposable vm but I’m guessing this is something else?