Windows Task Scheduler not running: read the Last Run Result, then fix the cause

Check these first

Task Scheduler records the last result of every task. Read it before changing anything.

# Last run, its result, the next run and how many runs were missed
Get-ScheduledTaskInfo -TaskName 'Nightly backup'

# The same from cmd.exe, with every setting
schtasks /query /tn "Nightly backup" /v /fo list

In the Task Scheduler window, the Last Run Result column and the History tab show the same. If the History tab is empty, history may be turned off: Enable All Tasks History in the Actions pane turns it on.

Last Run Result codes, and what they mean

Task Scheduler's own codes start with 0x4 (success and status) or 0x8004 (errors). The meanings below are Microsoft's, from the Task Scheduler error and success constants; they are written here without their leading zeros, so 0x00041301 appears as 0x41301.

A value that is not in this table, such as 0x1 or 0x2, is not one of Task Scheduler's own codes. Last Run Result shows the value the last run returned; for a script or program, look up what that value means in its own exit codes, and run the same command by hand to see its output. Microsoft notes that some results are Windows system error codes, which net helpmsg explains: net helpmsg 64, the example Microsoft gives, prints: The specified network name is no longer available. A result that starts with 0x8007 wraps a Windows error code in its last four hex digits, as 0x800710E0 wraps 4320.

Eight reasons a scheduled task does not run

In the order worth checking. The defaults quoted are Microsoft's.

Program/script:  powershell.exe
Add arguments:   -NoProfile -ExecutionPolicy Bypass -File "C:\jobs\nightly.ps1"
Start in:        C:\jobs

Get alerted when a task does not run

Last Run Result only helps when someone looks at it. A ping from the task, checked against the schedule outside the machine, reports the run that failed and the one that never started.

# C:\jobs\nightly.ps1
$ping = 'https://ping.lastping.dev/<your-monitor-id>'
function Send-Ping([string]$suffix = '', [string]$body = '') {
  try {
    if ($body) {
      Invoke-RestMethod "$ping$suffix" -Method Post -Body $body -ContentType 'text/plain' -TimeoutSec 10 | Out-Null
    } else {
      Invoke-RestMethod "$ping$suffix" -TimeoutSec 10 | Out-Null
    }
  } catch {}
}

Send-Ping '/start'
try {
  & 'C:\jobs\backup.exe' --target D:\backups
  if ($LASTEXITCODE -ne 0) { throw "backup.exe exited with code $LASTEXITCODE" }
  Send-Ping
} catch {
  Send-Ping '/fail' $_.Exception.Message
  exit 1
}

C:\jobs\backup.exe --target D:\backups
curl.exe -fsS -m 10 --retry 3 -o NUL https://ping.lastping.dev/<your-monitor-id>/%ERRORLEVEL%

What this catches

The script reports what it can see; the schedule reports the silence.

• ✓Never started: a disabled task, a user not logged on, battery power, a computer that was off, a condition that held it back or a script blocked by execution policy. No ping in the window opens an incident.
• ✓Failed: a non-zero exit code or an exception posts to /fail, and the alert goes out at once with the message on the incident.
• ✓Hung: the start ping arrived and the finish did not, so overrun detection opens an incident long before the 72-hour default stops the task.
• ✓The machine is gone: a dead disk, a reinstalled server or a laptop left in a drawer sends nothing, and that silence is an incident too.
• ✓Recovery: the next successful run closes the incident and sends a recovery notice.

Questions people ask

Front-loaded answers: the most important fact first.

• Why is my scheduled task not running?

  Read its Last Run Result first. The usual causes: the task is disabled or has no active trigger, it is set to run only when the user is logged on, the computer was on battery or switched off at the scheduled time, an earlier run is still going, or PowerShell's execution policy blocked the script.

• What does Last Run Result 0x1 mean?

  0x1 is not one of Task Scheduler's own codes. Last Run Result shows the value the last run returned; for a script or program, look up what that value means in its own exit codes. Run the same command by hand, as the same user and in the same Start in folder, and read its output.

• What does 0x41301 mean in Task Scheduler?

  SCHED_S_TASK_RUNNING: the task is currently running. If it stays there long after the job should have finished, the run is hung, and with the do not start a new instance setting it also blocks the next scheduled runs.

• What does 0x41303 mean in Task Scheduler?

  SCHED_S_TASK_HAS_NOT_RUN: the task has not yet run. Check that a trigger is enabled and its start time is in the past, and that the computer was on and allowed to run it.

• What does 0x80041320 mean?

  SCHED_E_USER_NOT_LOGGED_ON: the task will not run because the user is not logged on. Set the task to Run whether user is logged on or not.

• How do I get alerted when a scheduled task fails or does not run?

  Wrap the job in a PowerShell script that pings LastPing's /start URL, then the monitor URL on success or /fail with the error. Give the monitor the task's schedule and a grace window, and a task that never starts opens an incident too.

• Is this monitoring free?

  Yes. LastPing is free for individuals with no monitor cap. See how it compares to Healthchecks.io and Cronitor.