Comment 5 for bug 1560210

Okay, I can see that the resize is failing, probably because it tries to JSON-decode a None string.

Are you sure you can't find anything in the n-cpu logs ? You could also take a look on the n-cond logs.

Anyway, I'm not a virt expert, but I don't know if it's possible to resize an instance from an ESX-backed file to a libvirt one, I guess it's probably not supported but I'll double-check.