When executing the command "request system reboot" on an VMhost-based MX-series router where RE0 is the master, the RE0 reboot reason is observed as "0x4000: VJUNOS reboot".

user@MX_RE0> show chassis routing-engine no-forwarding

Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 35 degrees C / 95 degrees F
    CPU temperature             38 degrees C / 100 degrees F
    DRAM                      98248 MB (98304 MB installed)
    Memory utilization           4 percent
    5 sec CPU utilization:
      User                       3 percent
      Background                 0 percent
      Kernel                     6 percent
      Interrupt                  0 percent
      Idle                      91 percent
    1 min CPU utilization:
      User                       1 percent
      Background                 0 percent
      Kernel                     1 percent
      Interrupt                  0 percent
      Idle                      98 percent
    5 min CPU utilization:
      User                       1 percent
      Background                 0 percent
      Kernel                     1 percent
      Interrupt                  0 percent
      Idle                      99 percent
    15 min CPU utilization:
      User                       0 percent
      Background                 0 percent
      Kernel                     1 percent
      Interrupt                  0 percent
      Idle                      99 percent
    Model                          RE 2700 8C 128G
    Serial ID                      ABCD1234
    Start time                     2025-02-13 22:26:37 UTC
    Uptime                         21 minutes, 30 seconds
    Last reboot reason             0x4000:VJUNOS reboot
    Load averages:                 1 minute   5 minute  15 minute
                                       0.30       0.26       0.24

This reboot reason typically occurs due to a manual reboot initiated by the command "request system reboot" on the master Routing Engine (RE0). It indicates that the system rebooted intentionally, likely to perform system updates or changes.

Troubleshooting Steps:

1. Check RE0 Status:

  - Verify the current status of the RE0 to ensure it is acting as the **master** or **backup**.

  - To check the status, use the command:

   >show chassis routing-engine

  - Confirm that RE0 is the master. If the RE0 has switched over to RE1, proceed with the next steps.

2. If Switchover Occurred (RE0 to RE1):

  - If the Routing Engine has switchover from RE0 to RE1, collect the following logs for further analysis:

   - RSI- from both RE0 and RE1.

   - /var/logs from both RE0 and RE1.

  - Analyze the logs for any abnormalities or events leading to the switchover.

3. Check for Manual Reboot Command:

  - Confirm if the customer executed the "request system reboot" command on the master RE. If this was the case, the reboot reason 0x4000 may simply be due to this manual reboot.

  - Review any logged events or error messages in the system logs to identify if the reboot was intentionally triggered.

Resolution:

- If the reboot was triggered by the "request system reboot" command on RE0 (master), no further action is needed unless there are other underlying issues in the logs.

- If any abnormalities or unexpected events are found during the log analysis, further investigation into the system’s configuration and potential hardware issues may be required.