Acronis Backup: "The activity has failed due to a restart of the service" error

An operation in Acronis Backup Cloud fails with:

Error 0x1350001: The activity has failed due to a restart of the service.
| line: 0x7564da35b0f1eaf2
| file: e:\219\enterprise\common\tol\activity_workshop.cpp:88
| function: Tol::BaseRepairConditions::Result
| $module: mms_vsa64_10170