# Test driving OpenNebula.. unable to figure out how to convert a VM from vCenter

**URL:** <https://forum.opennebula.io/t/test-driving-opennebula-unable-to-figure-out-how-to-convert-a-vm-from-vcenter/14272>\
**Category:** Installation & Configuration\
**Created:** [October 7, 2025, 5:32pm UTC](https://forum.opennebula.io/t/test-driving-opennebula-unable-to-figure-out-how-to-convert-a-vm-from-vcenter/14272 "2025-10-07T17:32:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![skeer](https://avatars.discourse-cdn.com/v4/letter/s/7ea924/32.png) [@skeer](https://forum.opennebula.io/u/skeer)\
**Post date:** [October 7, 2025, 5:32pm UTC](https://forum.opennebula.io/t/test-driving-opennebula-unable-to-figure-out-how-to-convert-a-vm-from-vcenter/14272/1 "2025-10-07T17:32:17Z")

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So Im taking a look at Open nebula as a potential replacement for Vmware. I have downloaded MiniOne and have it all setup. I also grabbed OneSwap and have configured the config.yaml file with the info needed to connect to vcenter.

I can display Datacenters and VMs and the next step was to try to migrate one to Opennebula. However, I’m finding information hard to come by.

Number 1; There aren’t many examples of the cli syntax in the OneSwap repos/wiki.

Number 2; I’ve been unable to find any recent posts here in the forums related to migrating/converting from vmware.

So I’d like to ask, I am using this command string:

`oneswap convert ‘opentelemetrytest’ --vddk /home/user/vmware-vix-disklib-distrib/`

And it returns this:

`Downloading disks from vCenter storage to local disk`  
`% Total % Received % Xferd Average Speed Time Time Time Current`  
`Dload Upload Total Spent Left Speed`  
`0 0 0 0 0 0 0 0 --:–:-- --:–:-- --:–:-- 0`  
`curl: (22) The requested URL returned error: 404`  
`Deleting password files.`  
`Delete not enabled, leaving disks in /tmp/opentelemetrytest/conversions`  
`Delete not enabled, leaving /tmp/opentelemetrytest alone.`  
`download failed`

I have the vcenter url ([vcenter.domain.com](http://vcenter.domain.com)), as well as a vuser and vpass defined in config.yaml. But as a test I supplied all of those on the CLI, to no avail. I tried adding –verbose too, but I get no more content returned.

I’ve also tried directly to ESXI which also did not work. I am running everyone from one new Ubuntu 24 host with both OneSwap and open nebula installed.

Google results say to try using –skip-prechecks however that switch doesn’t seem to exist anymore. I have been unable to find info regarding what it’s trying to curl.

Can anyone help?

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**Author:** ![FrancJP](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.opennebula.io/francjp/32/7690_2.png) [@FrancJP](https://forum.opennebula.io/u/FrancJP)\
**Post date:** [October 9, 2025, 9:44am UTC](https://forum.opennebula.io/t/test-driving-opennebula-unable-to-figure-out-how-to-convert-a-vm-from-vcenter/14272/2 "2025-10-09T09:44:10Z")

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Hello @skeer

It looks like you hit an issue with `oneswap` failing with a `404` when trying to convert a VM from vCenter. That usually points to an auth or URL resolution problem on the vCenter side rather than a disk/transfer issue.

Some suggestions, while our engineers are trying to replicate the issue:

- Check if the OpenNebula host connects with the vCenter API you configured:  
`curl -k -u 'VCENTER_USER:VCENTER_PASS' https://<vcenter-host>/rest`  
(if you get the 404, please check hostname, port and that there’s no proxy).
- Make sure vCenter has enough privileges:  
`curl -k -u 'VCENTER_USER:VCENTER_PASS' https://<vcenter-host>/sdk`
- Run your conversion again with verbosity enabled:  
`oneswap --verbose convert <vm-id> ...`
- Confirm vCenter version compatibility
- Check the logs and share it here if possible:  
`/var/log/one/oned.log` and `/var/log/one/oneswap.log`

I already passed this issue to our engineer team, and hopefully they could give you a more detailed answer.

Cheers,

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**Author:** ![system](https://canada1.discourse-cdn.com/flex031/uploads/opennebula/original/2X/1/14d66f1130b9cd292905f575da9b68a9f574dd03.png) [@system](https://forum.opennebula.io/u/system)\
**Post date:** [November 8, 2025, 9:44am UTC](https://forum.opennebula.io/t/test-driving-opennebula-unable-to-figure-out-how-to-convert-a-vm-from-vcenter/14272/3 "2025-11-08T09:44:47Z")

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Closed on November 8, 2025, 9:44am UTC

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