Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
ThinkingArea: what it touches
Internal ChangesKind: in v2.1.282,
Internal ChangesSection of the release
What
Claude Code ships with a documentation table describing categories of errors the API can return. The thinking_signature category used to list only errors about thinking signatures. It now also covers the API rejecting the data in a redacted_thinking block, reported as "Invalid data in redacted_thinking block". Thinking is the model's reasoning before it answers, and a redacted_thinking block is reasoning returned in hidden form.
Why
In practice, the documentation now treats this rejection as the same kind of problem as a bad thinking signature.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeFixed sessions failing on every turn with an "Invalid data in redacted_thinking block" API error; Claude Code now drops the conversation's…
