NinjaOne Backup — Error 327: VSS Writer Error (Image Backup)
Audience: T2 Use when: Image backup fails with "Error 327" referencing a VSS writer failure during snapshot preparation.
Error 327 is more specific than Error 132 — it means a particular VSS writer explicitly reported an error during the pre-snapshot phase of an image backup job, rather than VSS failing generally.
How 327 Differs from 132
| Error | When It Fires | Root Cause Layer |
|---|---|---|
| 132 | VSS snapshot creation fails broadly | VSS infrastructure, DLLs, or any writer |
| 327 | A specific named writer fails during image backup snapshot prep | That writer's service or its underlying application |
Error 327 is specifically tied to the image backup plan (not file/folder backup). It means Lockhart started the image backup process, VSS began preparing the snapshot, and one writer signaled it could not participate.
Step 1 — Identify the Failing Writer
# Run immediately after the failure (writer state may reset after time)
vssadmin list writers
# Look for writers in:
# State: [6] Failed
# State: [5] Waiting for completion (stuck)
# Last error: anything other than "No error"
The writer name in the output tells you exactly which application is causing the failure.
Step 2 — Restart the Failing Writer's Service
# Match the writer name to its service and restart
# Common at dental sites:
# SqlServerWriter (dental databases: Dentrix Actian, DEXIS SQL, CS Imaging SQL)
Get-Service | Where-Object {$_.DisplayName -like "*SQL*"} | Select DisplayName, Name, Status
# Restart the specific instance — use single quotes for named instances
Restart-Service -Name 'MSSQL$ROMEXIS' -Force # example for Romexis
# System Writer (OS-level metadata)
Restart-Service CryptSvc
# WMI Writer
Restart-Service Winmgmt
# Hyper-V Writer (on HV01-style hosts)
Restart-Service vmms
After restarting:
# Confirm writer is back to Stable
vssadmin list writers
Step 3 — Trigger a Manual Backup Run
Once the writer is back to [1] Stable:
- NinjaOne → device → Backup → Run Backup Plan
- Monitor the activity log — the image backup should complete without Error 327
Special Cases at Dental Sites
SQL Server writers with dental databases:
Dental applications often run multiple SQL Server instances (MSSQL$DEXIS_DATA, MSSQL$ROMEXIS, MSSQL$CSISSERVER, etc.). Each instance registers its own SqlServerWriter. If any one of them is in a failed state, it can cause Error 327 on image backup.
# Find all SQL Server services and their status
Get-Service | Where-Object {$_.Name -like "MSSQL*"} | Select DisplayName, Name, Status
Restart any that are in a stopped or errored state before triggering the backup.
Windows Update in progress:
Error 327 sometimes fires when Windows Update is actively running or has just installed and is waiting for a reboot. The update process holds VSS writers in a pending state.
# Check for pending reboots
$rebootPending = @(
Test-Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired",
(Get-ItemProperty "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager" -ErrorAction SilentlyContinue).PendingFileRenameOperations
)
$rebootPending
If a reboot is pending: schedule a reboot, then run the backup.
Escalate to T3 If:
- Writer fails immediately after service restart
- Error 327 persists after reboot and service restart
- The failing writer is the NTDS writer on the only DC at the site