Error reference changederrors
Nearest release: v2.1.306, published under an hour after upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.
Upstream edited this page at 21 Oct 2026 01:33 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 21 Oct 2026 01:37 UTC.
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Recorded edits187to this page, all time
### Couldn't start the local listener that receives the browser sign-in ### Matches no tool · check for typos ### Failed to start OAuth callback server
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from line 79
7979| `Your account does not have access to Claude. Please login again or contact your administrator.` | [Authentication](#oauth-token-revoked-or-expired) |
8080| `API Error: 401 Invalid authentication credentials` | [Authentication](#api-error-401-invalid-authentication-credentials) |
8181| `Login expired · Please run /login` | [Authentication](#login-expired) |
82| `The browser can't return the sign-in to Claude Code automatically` | [Authentication](#couldnt-start-the-local-sign-in-listener) |
83| `Couldn't start the local listener that receives the browser sign-in. Try again.` | [Authentication](#couldnt-start-the-local-sign-in-listener) |
8284| `Failed to start OAuth callback server` | [Authentication](#failed-to-start-oauth-callback-server) |
8385| `Claude login not accepted · Run /login, then try again` | [Authentication](#claude-login-not-accepted) |
8486| `Artifacts need a claude.ai login` | [Authentication](#artifacts-need-a-claude-ai-login) |
from line 330
328330| `Your disk quota is full on the filesystem with Claude Code's temp directory <dir> (EDQUOT)` | [Tool errors](#disk-quota-or-temp-filesystem-is-full) |
329331| `The filesystem with Claude Code's temp directory <dir>, or your disk quota on it, is full (ENOSPC)` | [Tool errors](#disk-quota-or-temp-filesystem-is-full) |
330332| `Command output was lost: the temp filesystem at <dir> is full` / `is out of inodes` | [Tool errors](#disk-quota-or-temp-filesystem-is-full) |
333| `The command was not started: this computer's disk is full (ENOSPC)` / `(EDQUOT)` | [Tool errors](#disk-quota-or-temp-filesystem-is-full) |
331334| `File is not valid UTF-8. It may use a legacy encoding such as Windows-1252, Shift-JIS or GBK, or be binary` | [Tool errors](#file-is-not-valid-utf-8) |
332335| `the source file is not valid UTF-8 text` / `the source file is not valid UTF-16 text` | [Tool errors](#the-source-file-is-not-valid-utf-8-text) |
333336| `the source file has the replacement character U+FFFD` | [Tool errors](#the-source-file-is-not-valid-utf-8-text) |
from line 403
400403| `API Error: ANTHROPIC_FOUNDRY_RESOURCE must be a Foundry resource name` | [Configuration warnings](#anthropic-foundry-resource-must-be-a-foundry-resource-name) |
401404| `headersHelper not run — this workspace has no persisted trust` | [Configuration warnings](#headershelper-not-run) |
402405| `Invalid permission rule "..." was skipped: Malformed Tool(content) rule` | [Configuration warnings](#malformed-tool-content-rule) |
406| `matches no tool · check for typos` / `matches no known tool — check for typos` | [Configuration warnings](#matches-no-tool) |
403407| `... is not matched by file permission checks` | [Configuration warnings](#is-not-matched-by-file-permission-checks) |
408| `Write(<path>) never matches · use Edit(<path>)` / `Glob(<path>) never matches · use Read(<path>)` | [Configuration warnings](#is-not-matched-by-file-permission-checks) |
404409| `... has a wildcard before the rest of the command` | [Configuration warnings](#has-a-wildcard-before-the-rest-of-the-command) |
410| `allows any option at its * · use an exact value` | [Configuration warnings](#has-a-wildcard-before-the-rest-of-the-command) |
405411| `Denying Bash also turns off the PowerShell tool, so Claude has neither` | [Configuration warnings](#denying-bash-also-turns-off-the-powershell-tool) |
406412| `CLAUDE_CODE_DISABLE_1M_CONTEXT is set, but the 200K limit isn't enforced` | [Configuration warnings](#the-200k-limit-isnt-enforced) |
407413| `Model "<model>" isn't recognized · context assumed to be 200k tokens` | [Correct the window for a gateway or custom model ID](/docs/en/model-config#correct-the-window-for-a-gateway-or-custom-model-id) |
from line 1354
13481354* On other platforms, run `/login` again
13491355* If the login still doesn't save, see [Not logged in or token expired](/docs/en/troubleshoot-install#not-logged-in-or-token-expired) for the keychain unlock command and other credential-storage recovery steps
13501356
1351### Failed to start OAuth callback server
1357### Couldn't start the local listener that receives the browser sign-in
13521358
1353When `/login`, `claude auth login`, or `claude setup-token` signs you in through the browser, Claude Code opens a listening port on `127.0.0.1` so your browser can return the sign-in result to it. This message means Claude Code couldn't open that port, and the sign-in stops before a browser window or login URL appears:
1359Each of these messages from `/login`, `claude auth login`, or `claude setup-token` means Claude Code couldn't open the port on `127.0.0.1` where your browser returns the sign-in result.
13541360
1355```text theme={null}
1356Failed to start OAuth callback server: Failed to start server. Is port 0 in use?
1361With the notice that begins `The browser can't return the sign-in to Claude Code automatically`, the sign-in continues without that port. No browser opens, and the notice appears above a URL where you sign in instead:
1362
1363```text wrap theme={null}
1364The browser can't return the sign-in to Claude Code automatically. After you sign in, paste the code shown.
13571365```
13581366
1359If your message ends with `Is port 0 in use?`, the attempt to listen on the IPv4 loopback address `127.0.0.1` failed outright. Because the failure happens before a login URL exists, the `Paste code here if prompted` flow isn't available as a workaround.
1367With the message that includes `Couldn't start the local listener`, the sign-in stopped. That happens, for example, when you pipe input into `claude auth login`:
13601368
1369```text theme={null}
1370Couldn't start the local listener that receives the browser sign-in. Try again.
1371```
1372
13611373**What to do:**
13621374
1363* To sign in right away without the local listener: if you use a claude.ai subscription, run [`claude setup-token`](/docs/en/authentication#generate-a-long-lived-token) on a machine where sign-in works and set the token it prints as `CLAUDE_CODE_OAUTH_TOKEN` on this machine. Otherwise set `ANTHROPIC_API_KEY` to a key from the [Claude Console](https://platform.claude.com/settings/keys). [Authentication precedence](/docs/en/authentication#authentication-precedence) explains how Claude Code chooses between credentials.
1364* To use browser sign-in on this machine instead, Claude Code must be able to listen on `127.0.0.1`. If it runs inside a sandbox, check that the sandbox's policy allows listening on local ports, then run `/login` again. If it should be able to and still fails, run `/feedback` so the report includes your environment details.
1375* **`The browser can't return the sign-in to Claude Code automatically`**: you don't need to fix anything first. Open the URL shown under the notice in a browser and sign in. The browser then shows a code: paste it into Claude Code at the `Paste code here >` prompt, and the sign-in continues from there.
1376* **`Couldn't start the local listener that receives the browser sign-in`**: run the same command again. If it stops the same way, sign in with a token or API key instead of the browser. Or, if you piped input into `claude auth login`, run it in a terminal so it can take a pasted code.
1377* **To sign in with a token or API key instead of the browser**: if you use a claude.ai subscription, run [`claude setup-token`](/docs/en/authentication#generate-a-long-lived-token) on a machine where sign-in works. Then set the token it prints as the [`CLAUDE_CODE_OAUTH_TOKEN`](/docs/en/env-vars) environment variable on this machine. Otherwise set the `ANTHROPIC_API_KEY` environment variable to a key from the [Claude Console](https://platform.claude.com/settings/keys). [Authentication precedence](/docs/en/authentication#authentication-precedence) explains how Claude Code chooses between credentials.
1378* **To get the automatic browser return back**: Claude Code must be able to listen on `127.0.0.1`. If it runs inside a sandbox, check that the sandbox's policy allows listening on local ports, then sign in again. If listening should work there and the notice still appears, run `/feedback` so the report includes your environment details.
13651379
1380Before v2.1.305, the sign-in stopped as soon as the port couldn't be opened and showed no URL to sign in at. The message read, for example, `Failed to start OAuth callback server: Failed to start server. Is port 0 in use?`. On those versions, update Claude Code and sign in again, or sign in with a token or API key instead of the browser.
1381
13661382### Claude login not accepted
13671383
13681384You tried to start a [cloud session](/docs/en/claude-code-on-the-web), and the server refused to create it with a 401: it didn't accept the Claude login this machine sent, usually because the login expired or was revoked.
from line 2632
26162632Other messages report the same condition:
26172633
26182634* In an interactive session, a notification reads `Advisor will not activate on the main model (advisor is less capable); subagents may still use it and may use more tokens · /advisor`.
2619* At launch with the `--advisor` flag, a warning reads `"<advisor>" cannot advise "<main model>" (the advisor must be at least as capable as the main model). The advisor will not be used for the main model.` and the session starts anyway.
2635* When you launch with the `--advisor` flag in [non-interactive mode](/docs/en/headless), and the run isn't a [background session](/docs/en/agent-view), a warning goes to stderr and the run starts anyway. It reads `"<advisor>" cannot advise "<main model>" (the advisor must be at least as capable as the main model). The advisor will not be used for the main model.` An interactive session writes that warning only to the [debug log](#configuration-warnings).
26202636
26212637**What to do:**
26222638
from line 2652
26362652**What to do:**
26372653
26382654* Run `claude update` and restart Claude Code. Opus 4.7 needs v2.1.111 or later. Opus 4.8 needs v2.1.154 or later. Sonnet 5 needs v2.1.197 or later. Opus 5 needs v2.1.219 or later. Opus 5.5 needs v2.1.280 or later. Sonnet 5.5 needs v2.1.284 or later
2639* On the [stable release channel](/docs/en/setup#configure-release-channel), updating doesn't move you past the newest stable release, which can still be older than these versions. Move to the latest channel, then update
2640* If you can't upgrade, run `/model` and select Opus 4.6 or Sonnet 4.6 instead
2641* If you hit this in the [Agent SDK](/docs/en/agent-sdk/overview), upgrade the SDK package instead. Opus 4.8 needs TypeScript SDK v0.3.154 or later and Python SDK v0.2.88 or later. Sonnet 5 needs TypeScript SDK v0.3.197 or later. Opus 5 needs TypeScript SDK v0.3.219 or later. Opus 5.5 needs TypeScript SDK v0.3.280 or later. Sonnet 5.5 needs TypeScript SDK v0.3.284 or later
2642
2643### Effort isn't available with thinking turned off
2644
2645You turned [extended thinking](/docs/en/model-config#extended-thinking) off and ran at an [effort level](/docs/en/model-config#adjust-effort-level) above `high`. The model doesn't accept that combination, so the API rejected the request.
2646
2647```text theme={null}
2648API Error: Effort 'xhigh' isn't available with thinking turned off on this model · run /effort high to continue, or turn thinking back on (unset MAX_THINKING_TOKENS=0)
2649```
2650
2651The hint after the `·` varies by session: in a non-interactive session it reads `use --effort high (or the effortLevel setting)`, and in a session the Claude Desktop app runs it reads `you can lower effort to High`.
2652
2653**What to do:**
2654
2655* [Lower the effort level](/docs/en/model-config#set-the-effort-level) to `high` or below.
2656* Turn thinking back on, for example by unsetting [`MAX_THINKING_TOKENS`](/docs/en/env-vars) or removing [`"alwaysThinkingEnabled": false`](/docs/en/settings-reference#alwaysthinkingenabled) from your settings.
2657
2658Before v2.1.242, Claude Code showed the API's own message: `API Error: 400 output_config.effort 'xhigh' is not supported when thinking is disabled on this model. Use effort 'high' or below, or enable thinking.` Before v2.1.251, Claude Code sent the request at the effort level you set, so Opus 5 rejected every request above `high` with thinking turned off. Claude Code now sends effort `high` instead to models it knows reject the combination, such as Opus 5.
2659
2660### Thinking budget exceeds output limit
2661
2662The configured extended thinking budget exceeds the maximum response leng
2655* On
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