Could not connect to one or more vCenter Server systems: https://vcenterservername@domain.local:443/sdk

Error: 

Could not connect to one or more vCenter Server systems:
https://vcenterservername@domain.local:443/sdk

vpxd.log :

2018-09-26T10:01:50.551-06:00 error vpxd[7F7BA9DB6700] [Originator@6876 sub=vmomi.soapStub[20]] initial service state request failed, disabling pings. error=HTTP Status:500 'Internal Server Error'

2018-09-26T10:01:50.551-06:00 warning vpxd[7F7BA9DB6700] [Originator@6876 sub=Default] Closing Response processing in unexpected state: 3

2018-09-26T10:01:50.613-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceDiscovery opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Discovered license service endpoint URL: https://vcenterserver.fcicanada.com:443/ls/sdk

2018-09-26T10:01:50.614-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceDiscovery opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Using license service endpoint URL from cache: https://vcenterserver.fcicanada.com:443/ls/sdk

2018-09-26T10:01:50.614-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceProxy opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Using ls URL: https://vcenterserver.fcicanada.com:443/ls/sdk

2018-09-26T10:01:50.551-06:00 error vpxd[7F7BA9DB6700] [Originator@6876 sub=vmomi.soapStub[20]] initial service state request failed, disabling pings. error=HTTP Status:500 'Internal Server Error'

2018-09-26T10:01:50.551-06:00 warning vpxd[7F7BA9DB6700] [Originator@6876 sub=Default] Closing Response processing in unexpected state: 3

2018-09-26T10:01:50.613-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceDiscovery opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Discovered license service endpoint URL: https://vcenterserver.fcicanada.com:443/ls/sdk

2018-09-26T10:01:50.614-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceDiscovery opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Using license service endpoint URL from cache: https://vcenterserver.fcicanada.com:443/ls/sdk

2018-09-26T10:01:50.614-06:00 info vpxd[7F7B6AFDF700] [Originator@6876 sub=licenseServiceProxy opID=LicenseClientProcessInventoryLoadedAsync-50fa4cf3] Using ls URL: https://vcenterserver.fcicanada.com:443/ls/sdk

Fix : You need to see the postgres.log during the same time frame for the exact duplicate key ...and delete it 

root@vcenterserver [ /var/log/vmware/vpostgres ]# tail -f postgresql-26.log

2018-09-26 15:48:58.387 UTC 5ba3f052.a1a 0   LOG:  Updated instance status successfully.

2018-09-26 15:49:10.398 UTC 5babaa6b.8a0 3546684 VCDB vc ERROR:  duplicate key value violates unique constraint "pk_vpx_vm_virtual_device"

2018-09-26 15:49:10.398 UTC 5babaa6b.8a0 3546684 VCDB vc DETAIL:  Key (id, device_key)=(146, 8000) already exists.

2018-09-26 15:49:10.398 UTC 5babaa6b.8a0 3546684 VCDB vc STATEMENT:  INSERT INTO VPX_VM_VIRTUAL_DEVICE (ID, DEVICE_KEY, CONN_AL_GU_CONTROL_FLAG, CONN_CONNECTED_FLAG, CONN_START_CONNECTED_FLAG, CONN_STATUS, DEVICE_INFO_SUMMARY, DEVICE_INFO_LABEL, DEVICE_CONTROLLER_KEY, DEVICE_UNIT_NUMBER, DEVICE_TYPE, DEVICE_TEXT) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)

Take a snapshot . Connect to VCSA DB ..

Connect to VCSA database :

root@vcenterserver [ ~ ]# /opt/vmware/vpostgres/current/bin/psql -d VCDB -U postgres
psql.bin (9.4.15 (VMware Postgres 9.4.15.0-7748409 release))
Type "help" for help.

VCDB=# DELETE FROM vpx_vm_virtual_device where id='146' and device_key='8000';
DELETE 1
VCDB=#

Reboot the vCenter Server.