MXC sandbox startup failure

“MXC launcher: failed to create the process security environment: CreateProcessSecurityEnvironment failed (HRESULT = 0x80070020)”

Is this your bug? What gets counted gets fixed. Pile on.

Paste this into your agent. It files your report, with your error and version.

I hit this bug: rapsheet.dev/sheets/codex/issues/9289/file
Follow it to file my report. Show me the text before you send.

No install. No account. Public and anonymous. The link asks your agent for one report, nothing else. What it sends

Fading. 1 report or thumbs-up in the last 7 days and 2 the week before, down from 5 a week at the early-October peak.

Sandboxed shell and browser tools fail with MXC 0x80070020 on Windows. Commands and browser tools fail to start, with node_repl kernel exiting unexpectedly, and restarting Codex or Windows does not clear it.

Is this your bug?

File my report

Where: Windows sandbox tools
Error text: MXC launcher: failed to create the process security environment: CreateProcessSecurityEnvironment failed (HRESULT = 0x80070020)
Versions: 26.1002.7124.0 to 26.1023.50603
Platforms: Windows
How bad: Stops work: a core feature can't be used. Most reports say it blocks them completely.

Part of: Browser/Computer Use runtime won't start8 bugs

MXC launcher browser init failure38 people
Browser control fails at startup with sandbox-exec TIOCSTI error19 people
Browser control fails with trusted Node process exiting on Windows5 people
Computer use initialization fails3 people
MXC launcher startup failure3 people
Computer Use startup failure2 people
Node REPL calls time out2 people

Not quite your bug?

Shell and Node tools fail with MXC 0x80070020 on Windows2 people
Sandbox setup refresh fails308 people

Original reports9, newest first

Nov 2, 2026CreateProcessSecurityEnvironment failed (0x80070020)On GitHub#58977
Oct 28, 2026Windows app 26.1023.50603: Computer Use and shell fail to start with MXC 0x80070020 after full app restartOn GitHub#57652
Oct 26, 2026Error 0x80070020On GitHub#57069
Oct 19, 2026[Windows] Codex App sandbox fails to execute commands (HRESULT 0x80070020)On GitHub#55230
Oct 19, 2026The retry still fails with MXC error 0x80070020On GitHub#55224
Oct 18, 2026Windows: browser tools fail with MXC CreateProcessSecurityEnvironment error 0x80070020On GitHub#55100
Oct 9, 2026Windows: Tool startup fails with CreateProcessSecurityEnvironment error 0x80070020On GitHub#52752
Oct 9, 2026Codex for Windows: sandbox and browser tools fail to startOn GitHub#52547
Oct 8, 2026files not processingOn GitHub#52042