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Runtime Handler

The Runtime Handler is a necessary dependency for any Twilio Function to be able to execute. It bootstraps the environment for your Function, manages the initialization of the Twilio client, injects the Runtime Client into scope for your convenience, and other critical functions.



This is different from takes you to an external page) which is used for local development, but we will do our best to keep the version numbers up to date and in sync. This allows for a better local development experience, like using npm install.


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We follow the principle of Semantic Versioning(link takes you to an external page) to the best of our ability. We will only introduce breaking changes in major releases, new functionality in minor releases, and backwards compatible bug fixes in patch releases.

Release VersionDescription
2.0.1No changes for the end user. This is the new default version
2.0.0Node.js 18 is the new default
1.3.1Minor bump. No changes for the end user
1.3.0Local development changes for Node.js 16 support
1.2.5Updated local development dependencies
1.2.4Local development downstream dependencies update to remove vulnerable dependencies
1.2.3Local development changes for Node.js 14 support
1.2.2Bug fixes for local development. Same functionality as 1.2.1
1.2.1Adds better auto complete in local development when using TypeScript. Currently being rolled out as new default.
1.2.0Adds support for accessing and modifying incoming headers and cookies from the new event.request object
1.1.3Bug fixes and minor improvements
1.1.2Accessing SERVICE_SID or ENVIRONMENT_SID environment variables in local development will now cause a warning to be displayed
1.1.1Bug fixes and minor improvements
1.1.0The Twilio library is now lazy-loaded to improve the cold start time of Functions
1.0.2Provides fixes for bugs in the local development environment
1.0.1The previous default version, initial release of the Runtime Handler

Preview Versions

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The following versions are available as a preview of upcoming versions. They are not meant for production and might contain breaking changes between releases.

Previews are not covered by Twilio support agreements, and will not be supported via chat or paid phone support until after production launch. Twilio's engineers may handle customer help requests for some previews to improve those products for general availability release. Because our engineering team handles these help requests, responses may take longer.

There are currently no preview versions available.

Default Runtime Handler Version

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For projects where you don't have a specific Runtime Handler version specified, for example, new projects that you created through the Console, you might receive new Runtime Handler versions as we roll them out gradually to the customer base.

Follow the instructions below to pin the relevant version that you want to use. For new projects created through the Twilio Console, you'll see the default version of the Runtime Handler appear in the Dependencies section after you have deployed to your project for the first time.

It is important to set the correct version of the Runtime Handler, especially if you want to take advantage of the latest features. The process of setting the version varies depending on whether you're developing using the Console(link takes you to an external page) or programmatically, such as with the Serverless Toolkit or via the Serverless API. All methods are described below.



The version of Runtime Handler must be exact, such as 1.2.1. Version ranges are not supported.

For example, attempting to use latest or ^1.0.1 will fail when attempting to deploy

Twilio ConsoleServerless ToolkitServerless API

If you created your Function using the Console(link takes you to an external page), you can set the version of @twilio/runtime-handler via the Console UI. To begin, navigate to the Function Editor for the Service that you want to update. Then complete the following steps:

  1. Under Settings , click on Dependencies . This will open a new tab in the editor, which contains a list of your Node version and all npm modules and their versions
  2. Click the Edit button for @twilio/runtime-handler , enter your desired version, and click Update
  3. When ready, click the Deploy All button to deploy your Service with the updated Runtime Handler in place
Set Runtime Handler version in dependencies.

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