What causes "Failed to find component type %v with title %v" in sqshq/sampler?

Verify the component's title in the YAML matches exactly (including case and spaces) what the update request sends

Failed to find component type %v with title %v

Error message

Failed to find component type %v with title %v

What it means

Config.Update locates the component config matching a type and title via findComponent; if no component of the given type has the given title, it panics with "Failed to find component type %v with title %v". This guards the invariant that runtime updates must reference an existing configured component — a missing match means the update cannot be applied safely.

Source

Thrown at config/config.go:98

			if component.Title == componentTitle {
				return &c.SparkLines[i].ComponentConfig
			}
		}
	case TypeAsciiBox:
		for i, component := range c.AsciiBoxes {
			if component.Title == componentTitle {
				return &c.AsciiBoxes[i].ComponentConfig
			}
		}
	case TypeTextBox:
		for i, component := range c.TextBoxes {
			if component.Title == componentTitle {
				return &c.TextBoxes[i].ComponentConfig
			}
		}
	}

	panic(fmt.Sprintf(
		"Failed to find component type %v with title %v", componentType, componentTitle))
}

func readFile(location *string) *Config {

	yamlFile, err := ioutil.ReadFile(*location)
	if err != nil {
		log.Fatalf("Failed to read config file: %s", *location)
	}

	cfg := new(Config)
	err = yaml.Unmarshal(yamlFile, cfg)

	if err != nil {
		log.Fatalf("Failed to read config file: %v", err)
	}

	return cfg

View on GitHub (pinned to 9bc7ba732d)

Solutions

Verify the component's title in the YAML matches exactly (including case and spaces) what the update request sends
Re-read/reload the config before updating if components were recently added or removed
Replace the panic with an error return: change findComponent to return (*ComponentConfig, error) and have Update propagate it
Add a pre-check in the caller that the component exists before issuing an update

Example fix

// before
panic(fmt.Sprintf(
    "Failed to find component type %v with title %v", componentType, componentTitle))
// after
return nil, fmt.Errorf("failed to find component type %v with title %v", componentType, componentTitle)

Defensive patterns

Strategy: validation

Validate before calling

func componentExists(cfg *config.Config, ctype, title string) bool {
    // iterate configured components and compare Title/type before Update
    return findIndex(cfg, ctype, title) >= 0
}

Try / catch

func updateSafe(cfg *config.Config, ctype, title string, data []byte) (err error) {
    defer func() { if r := recover(); r != nil { err = fmt.Errorf("update failed: %v", r) } }()
    cfg.Update(ctype, title, data)
    return nil
}

Prevention

Keep update requests and YAML titles in sync (exact match, case-sensitive)
Reload config snapshots before issuing updates after edits
Refactor findComponent to return an error instead of panicking

When it happens

Trigger: Calling Update (e.g. from the web/API layer) with a componentType/title pair that does not exist in the loaded Config — wrong title casing, component removed from YAML, or mismatched type (textbox vs run-chart vs gauges...).

Common situations: Web UI or API client sending a stale title after the user renamed/removed the component in the YAML; programmatic updates constructing titles by string concatenation; case-sensitivity mismatches between config and request.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

AI-assisted analysis of sqshq/sampler@9bc7ba732d (2026-09-06). Data as JSON: /api/errors/4b0d578c16fe74c1. Report an issue: GitHub.