Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.274 ·

Stdio MCP servers that exit mid-initialize after a probe timeout now get one restart

Stdio MCP servers that exit right after a startup probe times out now get one automatic restart

TierYou'll noticehow much it should matter to you
Useful2my rating, 1 to 5
Signal1worth watching, 1 to 5
AreaMCPwhat it touches
KindBug Fixesin v2.1.274,
You'll notice

Stdio MCP servers that exit right after a startup probe times out now get one automatic restart

What

When Claude Code connects to an MCP server over stdio (standard input/output, used for local server processes), it sometimes runs a version-negotiation probe first. If that probe times out and the server process then closes while still initializing, Claude Code now recognizes this specific pattern - a likely slow-starting server that exits on requests sent before it's ready - and restarts the server once without the probe, using whatever time is left in the connection budget.

Previously, only a different failure (a version-negotiation error causing the connection to close) triggered a stdio server restart; a probe-timeout-induced close was not handled.

Why

This reduces false failures for MCP servers that are simply slow to start up, giving them a second chance to connect properly instead of failing outright.

See this entry in the whole of v2.1.274 →