Comment 5 for bug 1286099

After further investigation it was found, that this error only happens when NoopQuotaDriver is used (i.e. quotas *are not* enforced on purpose by Nova). So while this is still an error (and the error message is indeed rather misleading), it doesn't affect the way quotas work. To reproduce the bug ensure that /etc/nova/nova.conf on controller node has 'quota_driver=nova.quota.NoopQuotaDriver' setting (restart nova-api service if you have changed it).

Horizon user experience (as of J2 milestone) is probably not very good here, as it makes users think they *can* modify the quotas, when they actually *can't* do that, given the fact that NoopQuotaDriver is chosen. The proposed fix is to disable 'Modify Quota' button when quotas are disabled that way in Nova.