September 18, 2026
If a project has no CLAUDE.md, Claude Code reads AGENTS.md: added in v2.1.277
On 18 September 2026, Anthropic released Claude Code v2.1.277. In a project without CLAUDE.md, the AI agent now reads AGENTS.md, while claude -p and Agent SDK report an error and exit with code 1 instead of hanging. The release also fixes failures with --resume, plugin operation, Grep and Glob search, and launching the interface.
Previously, project rules for Claude Code were set through CLAUDE.md. Now, in a project without that file, the agent reads AGENTS.md. The setting is in /config → Project instructions, but it does not yet work in Bedrock, Vertex, and Foundry.
Automated runs. Previously, claude -p and Agent SDK could hang after an internal error and return no result. Now they report an error and exit with code 1. After --resume, a bug involving an empty text block has been fixed; it caused every subsequent request to fail with the message text content blocks must be non-empty.
Update. An installed Claude Code is updated with `claude update`, and its version can be checked with `claude --version`.
v2.1.277 remains a maintenance release: beyond AGENTS.md, it addresses failures around sessions, plugins, and the interface.
