SeleniumHQ/selenium · error · Error

Contexts must be an array of non-empty strings

Error message

Contexts must be an array of non-empty strings

What it means

Thrown by Network.setCacheBehavior() when the optional contexts argument is non-null but is not a non-empty array of non-empty trimmed strings. The client verifies Array.isArray, length > 0, and that every element is a string whose trim() is not empty, before attaching the contexts to the network.setCacheBehavior command. This guards against empty context IDs that the remote end would reject.

Source

Thrown at javascript/selenium-webdriver/bidi/network.js:389

  async setCacheBehavior(behavior, contexts = null) {
    if (!Object.values(CacheBehavior).includes(behavior)) {
      throw new Error(`Cache behavior must be either "${CacheBehavior.DEFAULT}" or "${CacheBehavior.BYPASS}"`)
    }

    const command = {
      method: 'network.setCacheBehavior',
      params: {
        cacheBehavior: behavior,
      },
    }

    if (contexts !== null) {
      if (
        !Array.isArray(contexts) ||
        contexts.length === 0 ||
        contexts.some((c) => typeof c !== 'string' || c.trim() === '')
      ) {
        throw new Error('Contexts must be an array of non-empty strings')
      }
      command.params.contexts = contexts
    }

    await this.bidi.send(command)
  }

  /**
   * Unsubscribes from network events for all browsing contexts.
   * @returns {Promise<void>} A promise that resolves when the network connection is closed.
   */
  async close() {
    if (
      this._browsingContextIds !== null &&
      this._browsingContextIds !== undefined &&
      this._browsingContextIds.length > 0
    ) {
      await this.bidi.unsubscribe(

View on GitHub (pinned to aa36b38e69)

Solutions

1. Pass an array of one or more non-empty string context ids, e.g. setCacheBehavior('bypass', ['ctx1','ctx2']).
2. Filter out empty/blank ids before calling: contexts.filter(c => typeof c === 'string' && c.trim() !== '').
3. Pass null (the default) to apply the cache behavior globally, avoiding the contexts check.

Example fix

// before
await network.setCacheBehavior('bypass', currentContextId) // string

// after
await network.setCacheBehavior('bypass', [currentContextId]) // array of non-empty strings

function assertContexts(contexts) {
  if (contexts === null) return null
  if (!Array.isArray(contexts) || contexts.length === 0 ||
      contexts.some((c) => typeof c !== 'string' || c.trim() === '')) {
    throw new Error('contexts must be a non-empty array of non-empty strings')
  }
  return contexts
}

function isNonEmptyStringArray(v) {
  return Array.isArray(v) && v.length > 0 &&
    v.every((c) => typeof c === 'string' && c.trim() !== '')
}

When it happens

Trigger: Calling setCacheBehavior('bypass', 'ctx1') (string not array), setCacheBehavior('bypass', []), setCacheBehavior('bypass', ['']), setCacheBehavior('bypass', [' ']), or setCacheBehavior('bypass', [123]).

Common situations: Passing a single context id string instead of an array; reusing a variable that was filtered to empty; including whitespace-only or null context ids copied from a stale context list.

Related errors

• Cache behavior must be either "${CacheBehavior.DEFAULT}" or
• Params must be an instance of AddInterceptParameters. Receiv
• Params must be an instance of ContinueRequestParameters. Rec
• Params must be an instance of ContinueResponseParameters. Re
• Params must be an instance of ProvideResponseParameters. Rec

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/7ff3175c19f88a48. Report an issue: GitHub.