Windows Server Backup intermittently fails trying to create a directory

Windows Server Backup (part of the Windows Essentials package) occasionally (about 1 time in 4 or 5) fails with the message below. I'm trying to create a system image as a way of recovering, in case the server's C drive should fail. Both scheduled and one-time backups sometimes fail.

This post is somewhat similar, but their problem is not intermittent and no solution is given. Also somewhat similar to this, but again there is no answer.

Here is the error report, from Windows Event Viewer:

- System 
Provider

[ Name] Microsoft-Windows-Backup [ Guid] {1DB28F2E-8F80-4027-8C5A-A11F7F10F62D}
EventID 517
Version 1
Level 2
Task 0
Opcode 0
Keywords 0x8000000000000000
TimeCreated
[ SystemTime] 2018-07-02T01:23:14.819937300Z
EventRecordID 104812
Correlation

Execution
[ ProcessID] 5288 [ ThreadID] 1292
Channel Application
Computer VGSERVER
Security
[ UserID] S-1-5-18

EventData
BackupTime 2018-07-02T01:21:18.772760000Z ErrorCode 0x8078014b ErrorMessage %%2155348299

Fault bucket -1563072837, type 5 Event Name: Windows Server Backup Error Response: Not available Cab Id: 0

Problem signature: P1: 3 P2: 1 P3: 0x8078014b P4: 0x80070005 P5: 0x8078014b P6: 0x8078014b P7: 0x8078014b P8: 0x00000000 P9: P10:

Attached files:
These files may be available here: C:\ProgramData\Microsoft\Windows\WER\ReportArchive\NonCritical_3_7566d81ba9329d2847af18f41d5591aebbc9543_00000000_1c5650c0

Analysis symbol: Rechecking for solution: 0 Report Id: 7d87c975-7d96-11e8-a2b6-002590eaf347 Report Status: 0 Hashed bucket: d4317c7a07f3fa12de2621ca4c7145c9