What causes "BYHOUR must be between 0 and 23" in Hmbown/CodeWhale?

Use a valid hour 0–23 (`BYHOUR=23` for 11 PM, not 24).

Hmbown/CodeWhale · error · anyhow::Error

BYHOUR must be between 0 and 23

Error message

BYHOUR must be between 0 and 23

What it means

In the HOURLY branch, an optional BYHOUR anchor must fit the 0–23 wall-clock hour range (parsed as u32, so anything above 23 fails, e.g. 24 or 99). BYHOUR here anchors the initial local wall-clock time; it is not a daily-only filter, so values beyond a valid hour are meaningless and rejected.

Source

Thrown at crates/tui/src/automation_manager.rs:351

                if interval_hours == 0 {
                    bail!("INTERVAL must be >= 1 for HOURLY schedules");
                }
                let byday = parts
                    .get("BYDAY")
                    .map(|value| parse_byday(&value.to_ascii_uppercase()))
                    .transpose()?;
                let anchor_hour = parts
                    .get("BYHOUR")
                    .map(|value| value.parse::<u32>())
                    .transpose()
                    .context("Failed to parse BYHOUR")?;
                let anchor_minute = parts
                    .get("BYMINUTE")
                    .map(|value| value.parse::<u32>())
                    .transpose()
                    .context("Failed to parse BYMINUTE")?;
                if anchor_hour.is_some_and(|hour| hour > 23) {
                    bail!("BYHOUR must be between 0 and 23");
                }
                if anchor_minute.is_some_and(|minute| minute > 59) {
                    bail!("BYMINUTE must be between 0 and 59");
                }
                Ok(Self::Hourly {
                    interval_hours,
                    byday,
                    anchor_hour,
                    anchor_minute,
                })
            }
            AutomationFrequency::Weekly => {
                for key in parts.keys() {
                    if key != "FREQ" && key != "BYDAY" && key != "BYHOUR" && key != "BYMINUTE" {
                        bail!(
                            "Unsupported RRULE field '{key}' for WEEKLY. Allowed: FREQ,BYDAY,BYHOUR,BYMINUTE"
                        );
                    }

View on GitHub (pinned to 0c42157ee5)

Solutions

Use a valid hour 0–23 (`BYHOUR=23` for 11 PM, not 24).
If you need multiple fire hours, switch to `FREQ=CRON;EXPR=9,17 * * * *`.
Range-check user-supplied hours before formatting the RRULE.

Example fix

// before
let s = AutomationSchedule::parse_rrule("FREQ=HOURLY;INTERVAL=24;BYHOUR=24")?; // bails: 0-23

// after
let s = AutomationSchedule::parse_rrule("FREQ=HOURLY;INTERVAL=24;BYHOUR=23")?;

Defensive patterns

Strategy: validation

Validate before calling

let hour: u32 = hour_input;
assert!(hour <= 23, "BYHOUR must be 0-23");
let rrule = format!("FREQ=HOURLY;INTERVAL=6;BYHOUR={hour}");

Type guard

fn valid_hour(h: u32) -> bool { h <= 23 }

Try / catch

match AutomationSchedule::parse_rrule(&rrule) {
    Ok(s) => s,
    Err(e) if e.to_string().starts_with("BYHOUR must be between 0 and 23") => { /* re-prompt for a 0-23 hour */ return Err(e) }
    Err(e) => return Err(e),
}

Prevention

Use 0–23 hours; 24 is never valid (use 0).
Validate hour fields at the form/config boundary.
Convert 12-hour AM/PM input to 24-hour before formatting.

When it happens

Trigger: parse_rrule("FREQ=HOURLY;INTERVAL=6;BYHOUR=24") or BYHOUR=25/830 in a HOURLY rule.

Common situations: Using 24 to mean end-of-day; off-by-one from thinking hours are 1–24; RFC 5545 BYHOUR lists like `BYHOUR=9,17` being pasted in (the comma makes it fail u32 parsing first, but single out-of-range values hit this check).

Related errors

AI-assisted analysis of Hmbown/CodeWhale@0c42157ee5 (2026-08-20). Data as JSON: /api/errors/5ab5da019b8ab3fd. Report an issue: GitHub.