Backup failed, then worked?

Wasn't home but PC was on at the time. Came home, had 2 emails sent to me.

First said it failed:

====================
2019-12-20T09:00:01:228-05:00 4472 I00000000: -----
2019-12-20T09:00:01:228-05:00 4472 I00000000: ATI Demon started. Version: 24.5.1.22510.
2019-12-20T09:00:01:360-05:00 4472 I00640000: Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
2019-12-20T09:00:01:360-05:00 4472 I00640002: Operation My disks started by schedule.
2019-12-20T09:00:18:784-05:00 4472 I00640000: Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
2019-12-20T09:00:18:784-05:00 4472 I013C0000: Operation: Backup
2019-12-20T09:00:18:784-05:00 4472 I0064000B: Priority changed to Low.
2019-12-20T09:02:17:311-05:00 4472 E02160015: Error 0x2160015: A backup error.
| trace level: error
| line: 0xa340ffd3416335cf
| file: c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\da_api\backup.cpp:353
| function: da_backup::Commit
| line: 0xa340ffd3416335cf, c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\da_api\backup.cpp:353, da_backup::Commit
| $module: disk_backup_vs_650
|
| error 0x70021: Failed to create volume snapshot.
| line: 0x8ba4fa0bac28bf6d
| file: c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\resizer\archive3\backup_partition.cpp:538
| function: `anonymous-namespace'::PartitionBackuper::Init
| line: 0x8ba4fa0bac28bf6d, c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\resizer\archive3\backup_partition.cpp:538, `anonymous-namespace'::PartitionBackuper::Init
| $module: disk_backup_vs_650
|
| error 0x10c443: Failed to unlock the volume snapshot.
| line: 0x3fec04e376b8a1a2
| file: c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\fdisk\win_snapshot.cpp:1196
| function: win_snapshot_core::SnapStart
| line: 0x3fec04e376b8a1a2, c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\fdisk\win_snapshot.cpp:1196, win_snapshot_core::SnapStart
| $module: disk_backup_vs_650
|
| error 0x10c46b: VSS writer 'System Writer' with class ID 'E8132975-6F93-4464-A53E-1050253AE220' has failed to process the snapshot.
| line: 0x3fec04e376b89da6
| file: c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\fdisk\win_snapshot.cpp:176
| function: `anonymous-namespace'::ObtainVSSFailReasonSuberror
| line: 0x3fec04e376b89da6, c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\fdisk\win_snapshot.cpp:176, `anonymous-namespace'::ObtainVSSFailReasonSuberror
| $module: disk_backup_vs_650
|
| error 0xfff0
| line: 0xbd28fdbd64edb8fb
| file: c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\common\error.cpp:317
| function: Common::Error::AddHResult
| line: 0xbd28fdbd64edb8fb, c:\jenkins_agent\workspace\mod-disk-backup\650\product\core\common\error.cpp:317, Common::Error::AddHResult
| code: 0x800423f2
| $module: disk_backup_vs_650
2019-12-20T09:02:17:362-05:00 4472 E013C0005: Error 0x13c0005: Operation has completed with errors.
| trace level: error
| line: 0x9f2c53c72e8bced8
| file: c:\bs_hudson\workspace\23\products\imager\demon\main.cpp:738
| function: main
| line: 0x9f2c53c72e8bced8, c:\bs_hudson\workspace\23\products\imager\demon\main.cpp:738, main
| $module: ti_demon_vs_22510
====================

Note the last time stamp, 2019-12-20T09:02:17:362-05:00

Then I get one that it worked:

=====================
2019-12-20T09:02:50:182-05:00 17732 I00000000: -----
2019-12-20T09:02:50:183-05:00 17732 I00000000: ATI Demon started. Version: 24.5.1.22510.
2019-12-20T09:02:50:219-05:00 17732 I00640000: Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
2019-12-20T09:02:50:220-05:00 17732 I00640002: Operation My disks started by schedule.
2019-12-20T09:02:51:160-05:00 17732 I00640000: Backup reserve copy attributes: format tib; need_reserve_backup_copy false;
2019-12-20T09:02:51:161-05:00 17732 I013C0000: Operation: Backup
2019-12-20T09:02:51:162-05:00 17732 I0064000B: Priority changed to Low.
2019-12-20T10:08:20:624-05:00 17732 I013C0006: Operation has succeeded.
==========
So it tried some 48 minutes later? It worked and was successful.

What was the cause of the error? According to a DIR of the C: drive shows plenty of free space?

32,218,501,120 bytes free

The C drive is an SSD and quite fast, so it wasn't like it was busy and couldn't respond? Never had this happen before?

Any reason why from the first e-mail that tells you something?

I do see this thread, https://forum.acronis.com/forum/acronis-true-image-2020-forum/backup-fa…, but I am on V 22510?

Also https://forum.acronis.com/forum/acronis-true-image-2020-forum/dont-crea…, but I deleted 2016 before installing 2020?