{"version":"2.1.224","anchor":"new-mcp-error-code","canonical_anchor":"new-mcp-error-code","heading":"New MCP error code","tier":"internal","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.224\/e\/new-mcp-error-code","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.224","markdown":"### New MCP error code\n\nMCP clients now recognise a new denied-issuer-echo error code.\n\n**What**\n\n`ISSUER_ECHO_DENIED` was added to the recognised error codes of both MCP client generations, alongside the existing rejected-auth-header and rejected-bearer codes.\n\n**Evidence**\n\n`ISSUER_ECHO_DENIED`\n\n- Area: MCP\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 3\/5"}