DHCP Server Service Failure Due to Jet Engine Lease Database Corruption (dhcp.mdb) — Windows Server 2019/2022

Indicators

• DHCP Server service stops unexpectedly and does not recover automatically
• Client endpoints fail to obtain IP addresses via DHCP — no local or internet connectivity
• Event ID 1014 logged in Windows System/DHCP event logs indicating DHCP database state error
• Event ID 1016 logged in Windows System/DHCP event logs indicating DHCP database state error
• Jet engine error code JET_errRecordNotFound present in operational event logs
• New endpoints or roaming users entering the office network cannot obtain IP addresses

Likely causes

• Sudden storage outages causing incomplete writes to the dhcp.mdb Jet engine lease state tracking tables
• Unclean OS shutdowns leaving the Jet database in an inconsistent or partially committed state
• Internal Jet engine database errors corrupting the active dhcp.mdb lease state tracking tables

Diagnostic steps

1. Navigate to C:\Windows\System32\dhcp\ and verify presence and integrity of dhcp.mdb and associated files (dhcp.tmp, j50.log, j50.chk)
   Confirms whether lease database files are present and identifies obvious file-level corruption or missing files
2. Open Event Viewer (eventvwr.msc) and review DHCP Server operational event log and System log. Filter for Event ID 1014 and Event ID 1016
   Confirms DHCP service failure is due to database state errors rather than network or authorization issues
3. In the same event logs, search for Jet engine error code JET_errRecordNotFound to identify specific database engine failure details
   Pinpoints the exact Jet engine error causing database failure and confirms corruption of lease state tracking tables
4. Verify auto-backup folder C:\Windows\System32\dhcp\backup\Jet\new\ exists and contains recent database snapshot — check file timestamps against last known good operation
   Determines whether a viable backup exists for restoration before proceeding with remediation

Resolution path

• Step 1 — Stop the DHCP Server service: Run 'net stop DHCPServer' in elevated command prompt or execute Stop-Service -Name DHCPServer -Force in PowerShell
• Step 2 — Backup corrupted database (for analysis): Copy C:\Windows\System32\dhcp\dhcp.mdb to a safe location before overwriting
• Step 3 — Restore database snapshot: Copy all files from C:\Windows\System32\dhcp\backup\Jet\new\ to C:\Windows\System32\dhcp\, overwriting corrupted dhcp.mdb and associated files
• Step 4 — Restart the DHCP Server service: Run 'net start DHCPServer' or execute Start-Service -Name DHCPServer and verify service starts without error
• Step 5 (if backup restore fails) — Recreate scope database: Delete corrupted database files under C:\Windows\System32\dhcp\, open dhcpmgmt.msc, recreate DHCP scope(s), and reconcile all configuration parameters (scope ranges, reservations, options) against documented configuration

Prevention

• Ensure DHCP Server host uses reliable storage with redundancy (RAID or equivalent) to prevent corruption from storage outages
• Configure host for graceful shutdown procedures with UPS protection to avoid unclean OS shutdowns that leave Jet database inconsistent
• Regularly verify DHCP auto-backup folder (C:\Windows\System32\dhcp\backup\Jet\new\) contains recent valid snapshots — supplement with external backup jobs targeting dhcp.mdb and backup folder
• Deploy Windows DHCP Failover configuration (load balance or hot standby mode) on Windows Server 2019/2022 so secondary DHCP server can serve leases if primary fails
• Consider scheduled exports using 'netsh dhcp server export C:\DHCPBackup\dhcp-config.txt all' to maintain configuration-level backup separate from database state

Tools

• Services.msc (Windows Services management console — start/stop DHCP service)
• Event Viewer / eventvwr.msc (review DHCP and System event logs for Event IDs 1014, 1016, JET_errRecordNotFound)
• dhcpmgmt.msc (DHCP Server management console — scope recreation and reconciliation)
• net stop / net start (command-line service control)
• File Explorer / xcopy / robocopy (database file backup restoration)

References

• Microsoft Docs — DHCP Server Backup and Restore