clear-checkpoint argument must be a checkpoint ID

Error message

clear-checkpoint argument must be a checkpoint ID

What it means

clearCheckpoint validates the argument to the 'clear-checkpoint' terminal command before parsing it. A checkpoint ID must have the form 'c<N>' (e.g. 'c2'), where the leading character is literally 'c'. If the first character is not 'c', the command rejects the argument because it cannot be a valid checkpoint ID.

Source

Thrown at pkg/terminal/command.go:3412

	if err != nil {
		return err
	}
	w := new(tabwriter.Writer)
	w.Init(t.stdout, 4, 4, 2, ' ', 0)
	fmt.Fprintln(w, "ID\tWhen\tNote")
	for _, cp := range cps {
		fmt.Fprintf(w, "c%d\t%s\t%s\n", cp.ID, cp.When, cp.Where)
	}
	w.Flush()
	return nil
}

func clearCheckpoint(t *Term, ctx callContext, args string) error {
	if len(args) == 0 {
		return errors.New("not enough arguments to clear-checkpoint")
	}
	if args[0] != 'c' {
		return errors.New("clear-checkpoint argument must be a checkpoint ID")
	}
	id, err := strconv.Atoi(args[1:])
	if err != nil {
		return errors.New("clear-checkpoint argument must be a checkpoint ID")
	}
	return t.client.ClearCheckpoint(id)
}

func display(t *Term, ctx callContext, args string) error {
	const (
		addOption = "-a "
		delOption = "-d "
	)
	switch {
	case args == "":
		t.printDisplays()

	case strings.HasPrefix(args, addOption):

View on GitHub (pinned to a23773e6c3)

Solutions

Prefix the argument with 'c': use 'clear-checkpoint c2' instead of 'clear-checkpoint 2'.
Run 'checkpoints' to list valid checkpoint IDs and use the exact ID shown.
Check the source: strconv.Atoi parses args[1:], so only the 'c'+digits form is accepted.

Example fix

// before
clear-checkpoint 2
// after
clear-checkpoint c2

Defensive patterns

Strategy: validation

Validate before calling

func validCheckpointArg(s string) bool { return len(s) >= 2 && s[0] == 'c' }
// before calling: if !validCheckpointArg(arg) { prompt user for 'c<N>' form }
// in the terminal: clear-checkpoint c<N>

Type guard

func isCheckpointID(s string) bool {
    if len(s) < 2 || s[0] != 'c' { return false }
    _, err := strconv.Atoi(s[1:])
    return err == nil
}

Prevention

Always copy the checkpoint ID verbatim from the 'checkpoints' command output (it already includes the 'c' prefix).
Validate the 'c<N>' format before invoking clear-checkpoint.
Avoid hand-typing IDs; use the listed ID to prevent missing or malformed prefixes.

When it happens

Trigger: Running 'clear-checkpoint' with an argument whose first character is not 'c', e.g. 'clear-checkpoint 2' or 'clear-checkpoint x1'. Note that an empty argument yields the separate 'not enough arguments' error.

Common situations: Users type the numeric checkpoint ID without the 'c' prefix, forgetting the format that 'checkpoints' prints (IDs are displayed as c1, c2, ...). Copy-paste of only the number, or habit from other debuggers that use bare integers.

Related errors

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/108bde616d900b20. Report an issue: GitHub.