@icecoke Got it. I worked through the steps and found where I transposed one of the variables incorrectly. I was able to complete all the steps and the VM is booting now as expected. Thanks again.

@icecoke Thank you.

I do have an added complication. This disk resides on an XOSTOR SR. Also, when gathering the VDIUSERDEVICE I get the following error:

"The uuid you supplied was invalid."

Is the VBDUUID parameter a typo of VDIUUID? Otherwise I don't see a command to obtain the VBDUUID for this step:
"VDIUSERDEVICE = xe vbd-param-get param-name=userdevice uuid=VBDUUID"

@DustinB Sure thing.

Yes, XCCP-ng 8.3 while applying the latest round on 3/12/25, kept up to date prior.
XOA Premium, version 5.103.1.
Guest was Windows Server 2019 Standard with XenServer VM Tools version 9.3.3.

I ran across this issue today and thought I would share as I didn't find any immediate results when looking for a solution. I had a VM that was in an unhealthy state where RDP would not connect and the console tab in XOA was blank.

I was in the process of applying updates to the pool and also could not migrate this VM to a different host. I proceeded to install the patches and this VM went offline during the updates after the toolstack restarted.

I tried to boot the VM on the host I had wanted to move it to and got the "SR_BACKEND_FAILURE_46 The VDI is not available not detached cleanly" error. I then tried to just boot the VM with the same result.

The fix was to boot the VM on the original host it had been running on before the shutdown. Hope this helps.