Symptoms:
HTTP Status 400 - An error occurred while sending an authentication request to the PSC Single Sign-On server - null
type Status report
message An error occurred while sending an authentication request to the PSC Single Sign-On server - null
description The request sent by the client was syntactically incorrect.
For vSphere 7.0, see: Logging in to vSphere Client "An error occurred while sending an authentication request" using vCenter Server shortname
VMware vCenter Server 6.5.x
This HTTP Status 400 error occurs because the VECS store STS_INTERNAL_SSL_CERT copied over the certificate chain during an upgrade or possibly improper certificate replacement.
To resolve the HTTP Status 400 - An error occurred while sending an authentication request to the PSC Single Sign-On server - null issue, update the STS_INTERNAL_SSL_CERT to the leaf certificate from MACHINE_SSL_CERT certificate store.
To update the STS_INTERNAL_SSL_CERT to the leaf certificate:
/usr/lib/vmware-vmafd/bin/vecs-cli entry getkey --store MACHINE_SSL_CERT --alias __MACHINE_CERT --output ~/entry__MACHINE_CERT-getkey.txt
openssl pkey -in ~/entry__MACHINE_CERT-getkey.txt -pubout -outform pem | sha256sum
openssl x509 -in ~/leaf_MACHINE_CERT.pem -pubkey -noout -outform pem | sha256sum
/usr/lib/vmware-vmafd/bin/vecs-cli entry create --store STS_INTERNAL_SSL_CERT --alias __MACHINE_CERT --cert ~/leaf_MACHINE_CERT.pem --key entry__MACHINE_CERT-getkey.txt
service-control --stop --all
service-control --start --all