CLAUDE_CODE_STARTUP_FAILURE_RESULTS
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.274, including the newest one read.
Version-mismatch startup failures now return structured JSON for SDK-driven sessions
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.274.
In the changelogs
3Releases whose published page names CLAUDE_CODE_STARTUP_FAILURE_RESULTS.
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v2.1.318
Three organization and config startup failures now always report a result
Every stream-json run now writes a startup-failure result for three org and config failures, without needing an opt-in variable
found in this entry's text, named in this entry
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v2.1.274
CLI-too-old failure now emits structured JSON in stream-json/SDK mode
Version-mismatch startup failures now return structured JSON for SDK-driven sessions
found in this entry's text
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v2.1.274
Startup-failure result payload gated behind CLAUDE_CODE_STARTUP_FAILURE_RESULTS
Startup failures can emit a structured result message when CLAUDE_CODE_STARTUP_FAILURE_RESULTS is set
named in this entry, found in this entry's text
First cited
2The earliest release whose published evidence quoted CLAUDE_CODE_STARTUP_FAILURE_RESULTS was v2.1.274, 16 Sep 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
1Build by build
42One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.