thinking-troubleshooting changedbuild-with-claude/thinking-troubleshooting
Nearest release: v2.1.268, published 5 hours before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Recorded here
Lines+8added
Lines−2removed
From line
56
where the diff opens
First seen
14 Aug 2026
this site's first read of the page
Recorded edits16to this page, all time
The whole hunk
from line 56, old and new numbered
/
from line 56
5656
5757## A 400 error says `"thinking.type.disabled"` is not supported
5858
59The request fails with a 400 error whose message reads:
59The request fails with a 400 error. On Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, and Claude Mythos 5, the message reads:
6060
6161```text wrap
62"thinking.type.disabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.
63```
64
65On Claude Mythos Preview, the only one of these models that accepts extended thinking, the message reads:
66
67```text wrap
6268"thinking.type.disabled" is not supported for this model. Thinking defaults to adaptive mode when not specified; use "thinking.type.enabled" with "budget_tokens" for extended thinking.
6369```
6470
65This happens on models where thinking is always on: Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, and Claude Mythos Preview reject `"disabled"`. All of these except Claude Mythos Preview also reject the error text's suggested `"thinking.type.enabled"`.
71This happens because thinking is always on for all of these models (see the [per-model configuration table](https://platform.claude.com/docs/en/build-with-claude/thinking-troubleshooting#rejected-configurations)).
6672
6773Omit the `thinking` parameter; these models think without any configuration. If your goal was to keep thinking text out of responses, use `display: "omitted"` instead of disabling thinking; see [Controlling thinking display](https://platform.claude.com/docs/en/build-with-claude/thinking#controlling-thinking-display).
6874
No line in this hunk matches that.