Acronis Backup: activity fails with error "The account server HTTP request failed. Request: POST :443/bc/idp/token HTTP/1.1" and various HTTP responses (504, 503, 500, 404, 302)

Activity fails with one of the following errors:

The account server HTTP request failed. Request: POST <DC URL>:443/bc/idp/token HTTP/1.1, response: 504

The account server HTTP request failed. Request: POST <DC URL>:443/bc/idp/token HTTP/1.1, response: 503

The account server HTTP request failed. Request: POST <DC URL>:443/bc/idp/token HTTP/1.1, response: 500

The account server HTTP request failed. Request: POST <DC URL>:443/bc/idp/token HTTP/1.1, response: 404

The account server HTTP request failed. Request: POST <DC URL>:443/bc/idp/token HTTP/1.1, response: 302