Sandbox is unavailable. Falling back to allowlist mode for this session

Support Help
1

Keep getting the error: “Sandbox is unavailable. Falling back to allowlist mode for this session.” on my mac. Is this a know issue?

3

Hey, this is a known issue we’re tracking. To narrow down the possible causes, I’ve got a few questions:

  1. What version of Cursor are you on? (Help > About)
  2. What macOS version are you using, and which chip is it, Intel or Apple Silicon?
  3. Does your team admin have sandbox enabled? Does this happen every time after restarting Cursor, or randomly during a session?

For now, allowlist mode should still work for approving commands, just without full sandbox isolation.

4

I’m also experiencing this issue using cursor-agent CLI Installed with Homebrew.
I see this always in the CLI.

Version: 2026.02.13-41ac335
MacOS version: Tahoe 26.3 on M1 (apple silicon)

An interesting detail, sandbox seems to work without warnings in the Cursor IDE, I only see this error in the CLI (although I cannot tell if there’s actually the same error in the background and the IDE falls back to the allowlist or does. proper sandboxing).

5

I get the same. The sandbox works in the editor but the CLI agent reports it’s unavailable.

agent v2026.02.13-41ac335, macOS Sequoia, M1. The sandbox is enabled in the team admin settings (network access disabled in the sandbox). I have a coworker on Tahoe 26.0.1 and it works for them.

6

I’m on 2026.02.27-e7d2ef6 now and the issue seems to be fixed.

7

Unfortunately 2026.02.27-e7d2ef6 doesn’t seem to have resolved it for me. I still get “Sandbox is unavailable. Falling back to allowlist mode for this session.” macOS Sequoia, M1.

8

Oddly, after restarting ghostty, the agent no longer shows that “sandbox unavailable” message on startup. But I’m not sure the sandbox is actually sandboxing.

If I tell it Write the line “hi” to ~/testfile.txt it prompts me to proceed, reject, add write to allowlist, or auto-run in sandbox. If I choose auto-run in sandbox, it runs the command successfully and creates the file. Surprising because that’s write access outside my workspace.