Claude Code API Error 400 Invalid Effort Level: Upgrade to 2.1.314 or Lower Effort

Claude Code keeps failing with API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Invalid effort level"}} turn after turn. Check your version first, then upgrade or lower effort.

What I saw: claude --version on this box printed 2.1.312 (Claude Code), so we are not on the fixed release yet. I also could not reproduce an organization admin effort cap on a personal account — that path is enterprise policy. The steps below separate what we ran from what the official CHANGELOG says.

What Invalid effort level means

The API rejected the effort level your session asked for. Anthropic’s Claude Code CHANGELOG for 2.1.314 states that when an organization’s admin caps a model’s effort, older builds failed turn after turn; 2.1.314 lowers the effort, retries, and tells you which level it used.

For how effort / ultrathink levels work, see Claude Code ultrathink and effort. Other 400-class errors are listed in Claude Code Errors.

What we actually ran

claude --version

Output:

2.1.312 (Claude Code)

So this CLI does not yet include the auto-lower-and-retry behavior. On a personal account with no org effort policy, you often will not see Invalid effort level at all. If you still do, treat an outdated build or a pinned high effort as more likely than a broken account.

Fixes in order

1. Upgrade to Claude Code ≥ 2.1.314

The fix is documented in 2.1.314: on an org effort cap, Claude Code lowers effort, retries, and reports the level used. Upgrade the same way you installed it, for example:

claude update

Then run claude --version again and confirm you are on ≥ 2.1.314.

2. If you cannot upgrade yet: lower effort yourself

In the session, use /model and pick a lower thinking / effort level. At launch you can also pass --effort (visible in claude --help on this box). Do not stay stuck on a level your org forbids.

3. Still failing: confirm org policy

Team / Enterprise admins can cap effort per model. Personal accounts usually have no such cap, so we could not reproduce that failure mode here. If coworkers succeed and you do not, compare the raw error with the admin policy before reinstalling.

Cause and fix

Situation	How I judged it	Fix
CLI < 2.1.314	I saw: claude --version → 2.1.312	Upgrade to ≥ 2.1.314
Org effort cap	I inferred from CHANGELOG 2.1.314	Upgrade for auto-lower; or /model / --effort
Personal account, no org policy	I saw: cannot reproduce org cap	Still upgrade; check pinned high effort
Other API 400	Needs full error body	Use the error hub

FAQ

Will Invalid effort level still appear after 2.1.314?

Per the CHANGELOG, the old fail-every-turn path is replaced by lower-and-retry. If you still get a 400, paste the full JSON — it may be a different invalid_request_error.

Is this related to ultrathink / xhigh?

Yes. Higher effort is more likely to hit an org cap. Levels are explained in the ultrathink / effort post.

How is this different from 401 OAuth or selected model?

401 is auth; see 401 OAuth token has expired. Wrong model names are covered in there’s an issue with the selected model. Invalid effort level is about the effort field, not the token or the model id.