vmware-vpxd will not start on vcenter 6.5 appliance / 503 Service Unavailable (Failed to connect to endpoint..)

Out of the blue I'm not able to connect to our vcenter anymore. Https gives this error:

503 Service Unavailable (Failed to connect to endpoint: [N7Vmacore4Http20NamedPipeServiceSpecE:0x00007fd784033680] _serverNamespace = / action = Allow _pipeName =/var/run/vmware/vpxd-webserver-pipe)

vpxd.log errors:

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] Execute result code: -1

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] SQL execution failed: INSERT INTO VPX_EVENT_PARTITION_LOOKUP (START_DATE, PARTITION_INDEX) VALUES (?,?)

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] Execution elapsed time: 1 ms

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] Statement diagnostic data from driver is 23505:0:7:ERROR: duplicate key value violates unique constraint "pk_vpx_event_partition_lookup";

--> Error while executing the query

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] Connection diagnostic data from driver is HY000:0:110:

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] Bind parameters:

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] [0]datatype: 10, size: 23, arraySize: 0

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] value = 2017-4-16 0:0:0.0

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] [1]datatype: 1, size: 4, arraySize: 0

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] value = 69

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [Vdb::IsRecoverableErrorCode] Unable to recover from 23505:7

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [Vdb::IsRecoverableErrorCode] Unable to recover from HY000:110

2017-05-12T16:21:43.691Z error vpxd[7FC2626CD700] [Originator@6876 sub=Default opID=EventManagerProcessJobs-74f7f84d] [VdbStatement] SQLError was thrown: "ODBC error: (23505) - ERROR: duplicate key value violates unique constraint "pk_vpx_event_partition_lookup";

--> Error while executing the query" is returned when executing SQL statement "INSERT INTO VPX_EVENT_PARTITION_LOOKUP (START_DATE, PARTITION_INDEX) VALUES (?,?)"

Tried to delete:

 DELETE FROM vc.vpx_event_partition_lookup where start_date='2017-04-16';

But it does not make any difference.

Any suggestions?