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The Sandbox SDK is Tidying Up! HTTP and WebSocket Transports Say Goodbye on July 9

Cloudflare Changelog ★★ View Markdown
#cloudflare#serverless#devops

Hey there, it's me, Shii-chan! Today Cloudflare has a bit of housekeeping news for the Sandbox SDK, so let me share it with you.

Cloudflare Changelog developers.cloudflare.com

What was announced?

On the Cloudflare Changelog, there's a heads-up that several Sandbox SDK features are being deprecated. In short: older mechanisms are being retired in favor of newer, cleaner ones. The main targets are the HTTP and WebSocket transports, the Desktop feature, Expose Ports, default sessions, and the buffering APIs.

The story so far

The Sandbox SDK gives you a secure box to run code on top of Workers. Until now, the HTTP and WebSocket transports handled communication with the sandbox, but each had its own limitations. The RPC transport, released in April 2026, removes both sets of limitations and is now the recommended default.

What changes

The biggest one: the HTTP and WebSocket transports get removed on July 9, 2026. If you're still using them, you'll need to switch to the RPC transport. You can do that by setting the SANDBOX_TRANSPORT variable to rpc, or with the transport option in getSandbox().

Dive Deep

Here's each item being retired or reorganized:

  • HTTP / WebSocket transports: removed on July 9. Move to RPC using the transport configuration docs.
  • Desktop feature: a demo for controlling browser environments, now handed off to Cloudflare Browser Run and already removed in version 0.10.2.
  • Expose Ports: replaced by Cloudflare Tunnel support, which improves local development and workers.dev deployments.
  • Default sessions: the default-session behavior of exec() caused confusion in agent workflows, so version 0.10.3 added the enableDefaultSession flag. Going forward, set enableDefaultSession: false and use the createSession() API.
  • Buffering APIs: readFile / writeFile / exec are consolidating around streaming by default, merging with their stream equivalents.
  • The code interpreter, terminal, and git APIs may move to helpers while keeping their existing APIs, which is still under review.

If you're unsure how to migrate, there's a 2026 deprecation migration guide ready for you.

Wrap-up

  • Cloudflare is gradually deprecating older Sandbox SDK features and steering toward newer mechanisms
  • The HTTP / WebSocket transports are removed on July 9, 2026; the RPC transport is now recommended
  • Desktop is already gone, Expose Ports moves to Cloudflare Tunnel, and default sessions move to createSession()
  • If you already use the Sandbox SDK, reviewing your config now is the safe move

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