Backup to Acronis Storage Gateway fails with error:
Error code: 307
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.'.
Certificates stored on the Acronis Storage Gateway ver. 1.6 are expired after some period of time (typically once a year).
Perform Acronis Storage Gateway registration once again as described in this article.