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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.238 Home All releases ←olderv2.1.237 v2.1.239newer→

Claude Code v2.1.238 20 Aug 2026

"MCP server not connected" now tells you why

You'll notice

Useful4 Signal2

MCP

"MCP server not connected" now appends the underlying failure so you know why.

What

When a tool call reaches an MCP server whose connection failed, the error message now appends the underlying failure text instead of ending at the server name. The suffix appears only when the server is in the failed state with an error recorded, and is suppressed entirely when the MCP subsystem is kill-switched; the stable second argument stays "MCP server not connected".

Details

Applied identically in both copies of the MCP client in the bundle.

Evidence

MCP server not connected

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.238 →