Hi, I was able to track this down, thanks to the help of Omer Frenkel: https://bugzilla.redhat.com/show_bug.cgi?id=1045484 However it did cost me several days to find out what went wrong, and I'd like to make some suggestions to prevent such errors in the future or make them at least documented somewhere: It turned out, that the JSON implementation which at least started in 3.1. was not complete and not supported. This was not documented anywhere (at least where I looked). So what can we do to improve this? My suggestions would be: 1. If a new feature gets developed and (partly) released the exact status of this feature should be documented in the wiki/release notes/code/wherever e.g. feature x does work via webadmin, REST-API it does not work via java-sdk, python-sdk and CLI it does work with data passed via XML and not with data passed via JSON. 2. To automate the check if the feature works as intended one could write jenkins jobs, e.g.: start a vm via rest-api with json data if it fails this feature does not work. I know that my second suggestion is quite a bit of work but ovirt would greatly benefit from the achieved robustness and bugs would be very much more easily traceable. what do you think? -- Mit freundlichen Grüßen / Regards Sven Kieske Systemadministrator Mittwald CM Service GmbH & Co. KG Königsberger Straße 6 32339 Espelkamp T: +49-5772-293-100 F: +49-5772-293-333 https://www.mittwald.de Geschäftsführer: Robert Meyer St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen