hashicorp/nomad · error

Error formatting: %w

Error message

Error formatting: %w

What it means

When the prefix supplied to `nomad volume status` matches more than one CSI volume, the command formats the candidate list and returns it (as an error) with `Error formatting: %w` if csiFormatVolumes itself fails. Note the formatting error is distinct from the intentional 'Prefix matched multiple CSI volumes' message, which is not a real failure but disambiguation output.

Source

Thrown at command/volume_status_csi.go:37

	if id == "" {
		return c.csiVolumesList(client, opts)
	}

	// get a CSI volume that matches the given prefix or a list of all matches if an
	// exact match is not found.
	volStub, possible, err := getByPrefix[api.CSIVolumeListStub]("volumes", client.CSIVolumes().List,
		func(vol *api.CSIVolumeListStub, prefix string) bool { return vol.ID == prefix },
		&api.QueryOptions{
			Prefix:    id,
			Namespace: c.namespace,
		})
	if err != nil {
		return fmt.Errorf("Error listing CSI volumes: %w", err)
	}
	if len(possible) > 0 {
		out, err := csiFormatVolumes(possible, c.json, c.template)
		if err != nil {
			return fmt.Errorf("Error formatting: %w", err)
		}
		return fmt.Errorf("Prefix matched multiple CSI volumes\n\n%s", out)
	}

	// Try querying the volume
	vol, _, err := client.CSIVolumes().Info(volStub.ID, nil)
	if err != nil {
		return fmt.Errorf("Error querying CSI volume: %w", err)
	}

	str, err := c.formatCSIBasic(vol)
	if err != nil {
		return fmt.Errorf("Error formatting CSI volume: %w", err)
	}
	c.Ui.Output(str)
	return nil
}

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Use a longer/volume ID prefix so exactly one volume matches, eliminating the multi-match path.
2. If using -t/-json, fix the template expression (test it with a simpler field like .ID).
3. List volumes first (`nomad volume status` with no argument) to get the exact ID.

Example fix

// before
nomad volume status web -t '{{.BadField}'
// after
nomad volume status 4e6c3f8a-... -t '{{.ID}} {{.Name}}'

// disambiguate before asking for a single volume
possible, _ := client.CSIVolumes().List(&api.QueryOptions{Prefix: id})
if len(possible) > 1 {
	for _, v := range possible { fmt.Println(v.ID) }
	return fmt.Errorf("prefix %q is ambiguous; pick one ID", id)
}

out, err := csiFormatVolumes(possible, json, tmpl)
if err != nil {
	return fmt.Errorf("Error formatting: %w", err)
}

When it happens

Trigger: `nomad volume status web` where multiple CSI volumes share the prefix `web`, and csiFormatVolumes fails (e.g. template rendering error with -t, or internal format error).

Common situations: Using a too-short ID prefix combined with `-t` templates referencing nonexistent fields; Go template syntax errors on the command line.

Related errors

• Prefix matched multiple CSI volumes %s
• error parsing: root should be an object
• invalid capacity_min: %v
• invalid capacity_max: %v
• Error formatting CSI volume: %w

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/d311bf2d032ea9ad. Report an issue: GitHub.