GoogleChrome/lighthouse · error · Error

${pluginName} supportedModes must be an array, valid array v

Error message

${pluginName} supportedModes must be an array, valid array values are "navigation", "timespan", and "snapshot".

What it means

Thrown by ConfigPlugin._parseCategory when a plugin category's 'supportedModes' is present (not undefined) but is not an array whose every element is one of 'navigation', 'timespan', or 'snapshot' (isArrayOfGatherModes). supportedModes restricts which page-load gather modes the category runs in. A string, object, or an array containing invalid/misspelled values triggers it.

Source

Thrown at core/config/config-plugin.js:161

      manualDescription,
      auditRefs: auditRefsJson,
      supportedModes,
      ...invalidRest
    } = categoryJson;

    assertNoExcessProperties(invalidRest, pluginName, 'category');

    if (!i18n.isStringOrIcuMessage(title)) {
      throw new Error(`${pluginName} has an invalid category tile.`);
    }
    if (!i18n.isStringOrIcuMessage(description) && description !== undefined) {
      throw new Error(`${pluginName} has an invalid category description.`);
    }
    if (!i18n.isStringOrIcuMessage(manualDescription) && manualDescription !== undefined) {
      throw new Error(`${pluginName} has an invalid category manualDescription.`);
    }
    if (!isArrayOfGatherModes(supportedModes) && supportedModes !== undefined) {
      throw new Error(
        `${pluginName} supportedModes must be an array, ` +
        `valid array values are "navigation", "timespan", and "snapshot".`
      );
    }
    const auditRefs = ConfigPlugin._parseAuditRefsList(auditRefsJson, pluginName);

    return {
      title,
      auditRefs,
      description: description,
      manualDescription: manualDescription,
      supportedModes,
    };
  }


  /**
   * Extract and validate groups JSON added by the plugin.

View on GitHub (pinned to 9515cd4e58)

Solutions

Use an array of valid modes: supportedModes: ['navigation','timespan','snapshot'] or a subset.
If you want all modes, omit supportedModes entirely (undefined is allowed and means unrestricted).
Double-check spelling: exactly 'navigation', 'timespan', 'snapshot' (lowercase).

Example fix

// before
category: {title:'X', supportedModes:'navigation', auditRefs:[...]}
// after
category: {title:'X', supportedModes:['navigation','snapshot'], auditRefs:[...]}

Defensive patterns

Strategy: validation

Validate before calling

const VALID = new Set(['navigation','timespan','snapshot']);
if (cat.supportedModes !== undefined) {
  if (!Array.isArray(cat.supportedModes) || !cat.supportedModes.every(m => VALID.has(m))) {
    throw new TypeError('supportedModes must be an array of navigation/timespan/snapshot');
  }
}

Type guard

const MODES = new Set(['navigation','timespan','snapshot']);
function isSupportedModes(v) {
  return v === undefined || (Array.isArray(v) && v.every(m => MODES.has(m)));
}

Try / catch

try {
  await ConfigPlugin.parsePlugin(plugin, name);
} catch (e) {
  if (/supportedModes must be an array/.test(e.message)) console.error('Check supportedModes spelling/array');
  throw e;
}

Prevention

Always use an array even for a single mode.
Spell modes exactly: navigation, timespan, snapshot.
Omit supportedModes when you want all modes.

When it happens

Trigger: Category sets supportedModes: 'navigation' (a string, not array), or supportedModes: ['nav','snapshot'] (typo 'nav'), or supportedModes: [123]. isArrayOfGatherModes returns false and config-plugin.js:161 throws.

Common situations: Using the singular mode name or abbreviations ('nav','timespans'). Passing a comma-separated string instead of an array. Misspelling a mode after upgrading to a Lighthouse version that added supportedModes.

Related errors

AI-assisted analysis of GoogleChrome/lighthouse@9515cd4e58 (2026-08-13). Data as JSON: /api/errors/31a3666c835383fb. Report an issue: GitHub.