Acronis Backup Cloud: backup fails wih "VSS writer 'System Writer' with class ID 'E8132975-6F93-4464-A53E-1050253AE220' has timed out" error"

Backup fails with:

Windows error: (0x800423F2) VSS writer 'System Writer' with class ID 'E8132975-6F93-4464-A53E-1050253AE220' has timed out. This may be caused by too intensive I/O on the machine at the backup start time. Try to re-schedule the backup to some different time. To troubleshoot VSS issues, download and run Acronis VSS Doctor available at https://www.acronis.com/en-us/personal/vss-diagnostic-free-tool/