{"version":"2.1.242","anchor":"clearer-errors-when-a-page-requests-an-unavailable-mcp-serve","canonical_anchor":"clearer-errors-when-a-page-requests-an-unavailable-mcp-serve","heading":"Clearer errors when a page requests an unavailable MCP server","tier":"notice","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.242\/e\/clearer-errors-when-a-page-requests-an-unavailable-mcp-serve","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.242","markdown":"### Clearer errors when a page requests an unavailable MCP server\n\nA page asking for an unavailable MCP server now gets one of three specific rejections.\n\n**What**\n\nThe single \"reserved server name\" rejection has been split into three distinct outcomes with separate counts: an internal host server name, an opaque server id, and a malformed manifest.\n\n**Details**\n\n- The error text now states that built-in Claude app servers are never exposed to pages as host servers.\n- It lists the connectors seen during the session so you can pick a valid `server` value.\n\n**Evidence**\n\n`internal_host_server_name`\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5"}