jdx/mise · error

timer unit '{name}' must set at least one of `on_boot_sec`,

Error message

timer unit '{name}' must set at least one of `on_boot_sec`, `on_unit_active_sec`, `on_unit_inactive_sec`, or `on_calendar`

What it means

A unit classified as a Timer must specify at least one scheduling directive. If none of `on_boot_sec`, `on_unit_active_sec`, `on_unit_inactive_sec`, or `on_calendar` is set, `from_toml` bails because the timer would never trigger.

Source

Thrown at src/system/systemd.rs:212

                (config.restart_sec.is_some(), "restart_sec"),
                (config.standard_output.is_some(), "standard_output"),
                (config.standard_error.is_some(), "standard_error"),
            ]
            .into_iter()
            .filter_map(|(is_set, field)| is_set.then_some(field))
            .collect::<Vec<_>>();
            if !service_only_fields.is_empty() {
                bail!(
                    "timer unit '{name}' cannot set service-only directive(s): {}",
                    service_only_fields.join(", ")
                );
            }
            if config.on_boot_sec.is_none()
                && config.on_unit_active_sec.is_none()
                && config.on_unit_inactive_sec.is_none()
                && config.on_calendar.is_none()
            {
                bail!(
                    "timer unit '{name}' must set at least one of `on_boot_sec`, \
                     `on_unit_active_sec`, `on_unit_inactive_sec`, or `on_calendar`"
                );
            }
        }
        if let Some(nice) = config.nice
            && !(-20..=19).contains(&nice)
        {
            bail!("service unit '{name}' has invalid `nice` value {nice}; expected -20 through 19");
        }
        if let Some(umask) = &config.umask
            && !valid_umask(umask)
        {
            bail!(
                "service unit '{name}' has invalid `umask` value '{umask}'; expected an octal access mask from 0000 through 0777"
            );
        }
        let wanted_by = config.wanted_by.unwrap_or_else(|| match kind {

View on GitHub (pinned to afd2eddd3a)

Solutions

1. Add a schedule, e.g. `on_calendar = "daily"` or `on_boot_sec = 30`.
2. Use `on_unit_active_sec`/`on_unit_inactive_sec` for relative periodic triggers.
3. If no schedule is wanted, make it a plain service instead by adding `exec_start` and removing timer-only fields like `randomized_delay_sec`.

Example fix

# before
[systemd.backup.timer]
# no schedule set

# after
[systemd.backup.timer]
on_calendar = "*-*-* 03:00:00"

const TIMER_KEYS: &[&str] = &["on_boot_sec", "on_unit_active_sec", "on_unit_inactive_sec", "on_calendar"];
fn timer_has_schedule(cfg: &toml::Value) -> bool {
    TIMER_KEYS.iter().any(|k| cfg.get(k).is_some())
}

When it happens

Trigger: Declaring `[systemd.<name>.timer]` (or a unit with a service-only-field-free config that had `randomized_delay_sec`, making kind Timer) without any of the four schedule keys.

Common situations: Creating a timer skeleton and forgetting the schedule; commenting out `on_calendar` while testing; copying a service block and only renaming it `.timer`.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• service unit '{name}' must set a non-empty `exec_start`
• timer unit '{name}' cannot set service-only directive(s): {}
• "{path_raw}".{id}: no recognized operation (block, source, o
• brew-cask: command_wrapper requires content or executable
• bootstrap service '{name}' cannot be both masked and running

AI-assisted analysis of jdx/mise@afd2eddd3a (2026-09-09). Data as JSON: /api/errors/17fe54615ee8cf4e. Report an issue: GitHub.