{"version":"2.1.290","anchor":"legacy-sse-fallback-now-releases-and-restores-its-state-and","canonical_anchor":"legacy-sse-fallback-now-releases-and-restores-its-state-and","heading":"Stricter failure handling when MCP servers reconnect","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.290\/e\/legacy-sse-fallback-now-releases-and-restores-its-state-and","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.290","markdown":"### Stricter failure handling when MCP servers reconnect\n\nMCP reconnects now restore earlier state if the older HTTP+SSE fallback fails, and a refused sign-in step-up fails with `adopt_refused`\n\n**Unclear.** Whether the legacy HTTP+SSE fallback path is switched on for any account is not known.\n\n**What**\n\nMCP servers are outside programs that give Claude extra tools. Claude Code now handles two reconnect failures more carefully:\n\n- Legacy HTTP+SSE fallback: when Claude Code retries a server using this older connection method, it first releases the earlier connection state and puts it back if the fallback fails.\n\n- Step-up reauthentication: when a server asks you to sign in again with more access and the new connection is not accepted in place of the old one, the reconnect now fails with `adopt_refused` and is thrown away. Before, that result was ignored.\n\n**Why**\n\nA failed reconnect is now less likely to leave a server half-connected or in a mixed state.\n\n- Flag `tengu_mcp_legacy_sse_fallback`: Not enough to say (read for one account on one subscription tier against v2.1.290; this account: no value returned, anonymous baseline: no value returned, compiled default: on) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: MCP\n- Tier: You'll notice\n- Useful: 1\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}