Acronis Storage Gateway: 'Failed to find some certificates in the chain or some of them are expired.'

Symptoms

Backup to Acronis Storage Gateway fails with error:

Error code: 307
Module: 626
LineInfo: 0x50E61E3E2E723B45
Fields: {"$module":"disk_bundle_vsa64_3917"}
Message: Internal error: Registration server call has failed with the following error: 'Failed to find some certificates in the chain or some of them are expired.'.