[ovirt-users] Data Center non-responsive, storage not loading, and psql errors after importing an ova

I posted about this a few months ago on Reddit when it happened the first time, and I have now repeated it on two more separate installations. I have a simple oVirt 4.2 hosted-engine setup, two hosts, with a qnap NAS as the shared NFS storage. I copied an ova file (exported from vmware) to the NFS storage. I then imported it by logging into the engine gui, going to "Virtual machines", selecting the host/file path/datacenter/etc, and starting the import. Once I started the import, I get an alert that it failed almost immediately, followed by a notice that the data center is in a non-responsive state. Clicking on the "storage" tab under Data Center, or going to the "Storage Domain" page directly yields the three ". . ." loading animation, which never ends. I can still see the storage mounts on the hosts, and I can move files to and from them. the engine.log file on the hosted-engine VM contains a lot of the following lines: Caused by: org.springframework.dao.DataIntegrityViolationException: PreparedStatementCallback; SQL [select * from getstorage_domains_list_by_imageid (?)]; ERROR: integer out of range Where: PL/pgSQL function getstorage_domains_list_by_imageid(uuid) line 3 at RETURN QUERY; nested exception is org.postgresql.util.PSQLException: ER ROR: integer out of range Where: PL/pgSQL function getstorage_domains_list_by_imageid(uuid) line 3 at RETURN QUERY at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.doTranslate(SQLStateSQLExceptionTranslator.java:102) [spring-jdbc.jar:4.3. 9.RELEASE] What I have tried: Restarting the hosted-engine service Restarting nfs and vdsm services Rebooting the hosted-engine Rebooting both hosts Entering an exiting maintenance mode (one host never came out of maintenance, and refuses to with the error " General command validation failure ") Any idea what might have happened? And what should I have done to try to rectify it? Entering maintenance mode and restarting services seems to have made things much worse.