Acronis Backup Cloud: backup fails with TLS/SSL-related errors

Symptoms

Backup fails with an SSL/TSL-related error:

Error code: 43712912
Fields: {"$module":"disk_bundle_vsa64_15300","function":"astor_get_space_usage","path":"/"}
Message: SSL protocol error

In PCS log, you can find this error:

TLS connect failed with error 'error:1409441B:SSL routines:ssl3_read_bytes:tlsv1 alert decrypt error'

Cause

The error indicates a network configuration issue in the environment where the product is installed.