i have same problem, when upgrading from vCSA 6.0 to vCSA 6.5
In the vpxd.log file, i see entries:
2018-11-20T13:16:49.523Z error vpxd[7F915ABAC800] [Originator@6876 sub=Default] [VdbStatement] Execute result code: -1
2018-11-20T13:16:49.523Z error vpxd[7F915ABAC800] [Originator@6876 sub=Default] [VdbStatement] SQL execution failed: INSERT INTO VPX_ENTITY (ID, NAME, TYPE_ID, PARENT_ID) VALUES (?, ?, ?, ?)
2018-11-20T13:16:49.523Z error vpxd[7F915ABAC800] [Originator@6876 sub=Default] [VdbStatement] Execution elapsed time: 32 ms
2018-11-20T13:16:49.523Z error vpxd[7F915ABAC800] [Originator@6876 sub=Default] [VdbStatement] Statement diagnostic data from driver is 23503:0:7:ERROR: insert or update on table "vpx_entity" violates foreign key constraint "fk_vpx_ent_ref_vpx_ent_type";
--> Error while executing the query
on this error i found VMware Knowledge Base Article: https://kb.vmware.com/s/article/57738
May be this helps...