Claude Code v2.1.277

Claude Code v2.1.277 was released on September 18, 2026.

Summary

Claude Code 2.1.277 now reads AGENTS.md as project instructions when CLAUDE.md isn't present, making it easier to configure your setup. We've also improved stability with fixes for hanging sessions, conversation failures, and proxy handling that should smooth out your workflow...

Release Notes

• Added AGENTS.md support: in a project with no CLAUDE.md, Claude Code reads AGENTS.md instead; change it under "Project instructions" in /config (not yet on Bedrock, Vertex or Foundry)
• Added CLAUDEGATEWAYPROXYISEGRESSBOUNDARY=1 for Claude apps gateways whose only egress is a forward proxy: every outbound request hands the proxy the hostname instead of resolving it locally
• Added an optional headers: map on Claude apps gateway upstreams, to send static headers to a proxy you run in front of a provider
• Added a line saying a background task's update is waiting when it finishes while a panel such as /tasks is open
• Fixed claude -p and Agent SDK sessions that could hang with no result after an internal error; they now report the error and exit with code 1
• Fixed conversations failing every request with "text content blocks must be non-empty" when an earlier assistant turn held an empty text block beside other content, including after --resume
• Fixed being unexpectedly logged out when an older Claude Code build (for example an IDE extension's bundled CLI) runs on the same machine as the current one
• Fixed interactive start-up hanging or showing an error for ANTHROPICAPIKEY users when ~/.claude.json holds a malformed customApiKeyResponses value
• Fixed update checks erroring every 30 minutes, and claude update hanging when a minimum or maximum version is set, if a proxy returns an invalid version; a malformed minimumVersion is now ignored
• Fixed claude update on winget- or apk-managed installs reporting "up to date" when the version lookup failed
• Fixed claude plugin install sometimes failing and breaking the installed copy when reinstalling a plugin version that a session or another program was using; an unchanged copy is now left alone
• Fixed Grep and Glob reporting no matches when the search could not start because the system was out of processes, memory or file handles; they now return an error saying so
• Fixed the Write tool silently ending the turn as a declined permission when the target path is an existing directory; it now reports a clear error
• Fixed the Edit tool treating an escaped backslash followed by uXXXX text as a \uXXXX escape, which could make an edit of a non-ASCII character rewrite an escaped backslash sequence instead
• Fixed the Edit tool reporting "Invalid regular expression: regular expression too large" instead of "String not found in file" when a very large edit containing non-ASCII text did not match the file
• Fixed a turn ending early with "Path contains null bytes" when a tool call's file path contained \u0000 written as an escape sequence; escaped control characters now stay as literal text
• Fixed background sessions (claude --bg) exiting when a plugin's LSP server exited or closed its stdin
• Fixed a crash ("Type error") when opening /mcp or /plugin manage with a malformed claudeAiMcpEverConnected value in ~/.claude.json
• Fixed a crash at launch when ~/.claude.json holds a malformed theme value
• Fixed a crash ("unrecoverable interface error") when the prompt held text containing terminal color codes, for example a prompt recalled from history or text loaded from the external editor
• Fixed a crash when resuming a session whose saved history holds an assistant message stored as a plain string
• Fixed sessions on slow or heavily loaded machines sometimes exiting with "Claude Code exited after an unrecoverable interface error" when the first spinner appeared
• Fixed a rare case where the screen could stop updating for the rest of the session after an internal rendering error
• Fixed a rare case on Windows where a turn could stop with an error such as "Out of memory" right after Claude replied, so that reply's tool calls never ran
• Fixed sessions continued after /clear (restart, --continue, --resume) missing part of their first message when a SessionStart hook printed output, causing a full prompt-cache miss
• Fixed messages from other agents (such as a subagent's SendMessage) that arrived mid-turn showing up below the "Ran N shell commands" row instead of where they arrived
• Fixed the "copied" notice not appearing after drag-selecting text in the fullscreen /resume picker and other panels that cover the prompt area
• Fixed $TMPDIR expanding empty in Bash commands that run outside the sandbox while sandboxing is enabled
• Fixed WebFetch and WebSearch in Cowork cloud sessions not telling Claude why a request was refused, such as a used-up fetch budget or an admin policy
• Fixed the Claude apps gateway's telemetry relay ignoring a collector hostname or domain listed in NOPROXY when a proxy is set
• Fixed one malformed strictKnownMarketplaces or blockedMarketplaces entry silently disabling the whole enterprise marketplace policy
• Fixed failed auto-updates leaving large staged downloads behind in ~/.cache/claude/staging
• Fixed /plugin not stripping terminal control characters from messages on the Installed tab, such as the error of a failed plugin update
• Fixed /plugin → Installed and /skills crashing when a skill or legacy command is named like a built-in Object property such as constructor or toString
• Fixed /plugin closing with no message when every install in a multi-select failed
• Fixed uninstalled plugins reappearing as "failed to load" rows in /plugin Installed, and Remove not clearing such a row
• Fixed plugins from the official marketplace being recorded without their commit in installedplugins.json, and installedplugins.json keeping the old commit after updating a pinned-commit plugin
• Fixed plugin reload previews keeping every previewed copy of a plugin archive unpacked until exit, and overwriting the cached --plugin-url archive a reload falls back to when its download fails
• Fixed Remote Control session bookkeeping failing when ~/.claude.json holds a malformed placeholder record
• Fixed the error after a revoked claude.ai login blaming an expired Anthropic profile; it now leads with /login
• Fixed typed or pasted text occasionally coming out scrambled in the claude agents dispatch input during key repeat or very fast input
• Fixed a crash ("unrecoverable interface error") when resuming a session whose saved transcript contains a stop hook summary without a well-formed hook list
• Fixed Enter on a selected agent panel row doing nothing when keybindings.json rebinds Enter in the Chat context, for example to chat:queueSubmit
• Fixed PDF page reads on Windows failing when the working folder's path is long (about 120 characters or more)
• Fixed a headless resume (claude -p --resume, the SDK, a VS Code extension window reload) starting the session's cost and usage totals at

View original release

Other Recent Claude Code Releases

• v2.1.280 (September 22, 2026)
• v2.1.275 (September 17, 2026)
• v2.1.274 (September 16, 2026)
• v2.1.273 (September 15, 2026)
• v2.1.272 (September 14, 2026)

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