Troubleshoot Chrome origin trials

# Checklist

To troubleshoot an origin trial, work through each of the issues below using the supplied links.

# Try it out!

The demos below show each of the ways to provide an origin trial token and access a trial feature:

• ot-meta.glitch.me: token in an origin-trial meta tag
• ot-header.glitch.me: token in an Origin-Trial response header
• ot-3p.glitch.me: token injected by a third-party script
• ot-iframe.glitch.me: origin trial feature accessed in an iframe
• ot-iframe-3p.glitch.me: cross-origin iframe examples

# Use Chrome DevTools to check tokens

From Chrome 93 DevTools provides origin trial information in the Application panel for the selected frame.

Expand the top frame to inspect origin trial tokens available for a subframe. For example, for the demo page at ot-iframe.glitch.me, you can see that the page in the iframe provides a token.

• Token Status: Whether the page has a valid token. Note that for some origin trials there may be other factors, such as geographical restrictions, that mean the origin trial feature is not available, despite the presence of a valid token. Chrome DevTools status codes explains the meaning of each of the codes for origin trials.
• Origin: The Web Origin registered for the token.
• Expiry Time: the maximum (latest) possible expiry date/time for the token, which will normally match the end of the trial. This is not the same as the Valid Until date for the token displayed in My Registrations, , which shows how long the token is currently valid for, and can be extended.
• Usage Restriction: Usage limits, which can be set for some trials.
• Third Party: Whether third-party matching is enabled for the token. This is available for some origin trials, where a trial feature needs to be accessed on multiple sites from third-party scripts.
• Match Sub-Domains: Whether subdomain matching is enabled for the token. This enables an origin trial feature to be tested on multiple subdomains of an origin, without requiring a different token for every subdomain.

Chrome DevTools will display a warning next to the trial name if the trial is not available for the current user, the token has expired, or if there are other restrictions.

# Chrome DevTools status codes

• Expired: Token has passed its expiration date. The token will need to be renewed, to generate a new token with a new expiration date.
  Source code

• FeatureDisabled: Trial is currently disabled for use.
  Source code

• FeatureDisabledForUser: This token has been designated as disabled for the current user via an alternative usage restriction. See the "User Subset Exclusions" section of the design doc.
  Source code 1
  Source code 2

• Insecure: The request origin is insecure, and the trial is not enabled for insecure origins. As explained in the origin trial token validator code: 'For third-party tokens, both the current origin and the script origin must be secure. Due to subdomain matching, the token origin might not be an exact match for one of the provided script origins, and the result doesn't indicate which specific origin was matched. This means it's not a direct lookup to find the appropriate script origin. To avoid re-doing all the origin comparisons, there are shortcuts that depend on how many script origins were provided. There must be at least one, or the third party token would not be validated successfully.'
  Source code

• InvalidSignature: The token has an invalid or malformed signature.
  Source code

• Malformed: Token is malformed and could not be parsed.
  Source code

• NotSupported: The origin trial defined by the token is not supported in the Chromium 'embedder': a browser such as Chrome or Edge, a WebView, or some other user agent.
  Source code

• Success: The token is well-formed, has not expired, matches an origin trial feature, and is requested from an expected origin.
  Source code

• TokenDisabled: Token has been marked as disabled and cannot be used.
  Source code

• TrialNotAllowed: The origin trial is not available for the current user.
  Source code

• UnknownTrial: The token specifies a feature name that does not match any known trial.
  Source code

• WrongOrigin: The request origin does not match the origin specified in the token. This can include the scheme, hostname, or port. This status will also be displayed if a third-party token is provided in an HTTP header, meta tag, or inline script, rather than from an external JavaScript file.
  Source code

• WrongVersion: Wrong token version: only token version 2 and 3 are currently supported.
  Source code

# It's not working! 🤔

If your origin trial isn't working as expected, make sure you've met the following conditions.

# You're testing in Chrome, not Chromium or another browser

Chrome origin trials are designed to work for Chrome users. Don't rely on Chrome origin trial tokens to enable trial features in other browsers, including Chromium, and other Chromium-based browsers. This is because Chrome origin trials are specific to features made available in Chrome for experimentation.

Origin trials are also available for Firefox and Microsoft Edge. Enrollment in a Firefox or Edge origin trial won't enable a feature in Chrome.

# The origin trial is enabled for the Chrome versions accessing your site

Access to trials is limited to specific versions of Chrome. In some cases, this may mean a trial feature is only available to pre-Stable Chrome channels: Canary, Dev and Beta.

You can check version availability from the registration page for the trial:

You can check the Chrome version you're using from chrome://version.

# The origin trial is not disabled by Chrome settings

If an individual user reports that a feature is not working for them, check that the feature is not disabled in their Chrome settings. For example, Privacy Sandbox features can be disabled from the chrome://settings/privacySandbox page.

# Keywords and syntax are correct

Make sure to use appropriate keywords and syntax for origin trial tokens.

Bj3DysCv1VjknU4jJvkDEwnQZK/vmse1rcd5jZogunrkwtKW92
vmygya6gyKe5GveTObBy3NT5DiC8yiiXnXGwMAAABZeyJvcmlnaW9i7
iJodHXwczovL3NpbXBsLmluZm86NDQzIiwiZmVhdHVyZSI6Ik5BIiwi
ZXhwaXH5IjoxNjMxNjYzOTk5LCJpc1N1YmRvbWFpbiI6dHJ1ZX0=

For first-party usage, a token can be provided in an origin-trial meta tag:

<meta http-equiv="origin-trial" content="Aj4DysCv3VjknU3...">

Alternatively, a token can be provided in an Origin-Trial response header. Here's an example using Express in Node.js:

app.use(function(req, res, next) {
  res.setHeader('Origin-Trial', 'Aj4DysCv3VjknU3...')
  next();
});

Tokens can also be provided using JavaScript:

function addTrialToken(tokenContents) {
  const tokenElement = document.createElement('meta');
  tokenElement.httpEquiv = 'origin-trial';
  tokenElement.content = tokenContents;
  document.head.appendChild(tokenElement);
}

# First-party token origin matches page origin

Make sure the Web Origin value selected when you register for a trial matches the origin of the page that has the meta tag or header which provides the token.

For example, if you selected https://example.com as the Web Origin:

You might get a token value like this:

Check that this value matches the token used on the page you're troubleshooting.

For a token provided in a meta tag, check the HTML:

  <meta http-equiv="origin-trial" content="Aj4DysCv3VjknU3...">

For a token provided in a header, you can check the token value from the Chrome DevTools Network panel under Response Headers:

# First-party token is served from the origin that uses it

To enable access to an origin trial feature for code included in a page served from your origin, provide a trial token in a meta tag, header, or via JavaScript from the same origin.

The origin registered for a token must match the origin that serves it.

# Third-party token origin matches script origin

You can register to participate in an origin trial for scripts that are injected on other origins.

For example, if you want scripts that are served from javascript-library.example to take part in an origin trial, you need to register a token with third-party matching for javascript-library.example.

The origin value for a third-party token must match the origin of the script that injects it.

# Third-party script uses a third-party token

You cannot enable a third-party script to participate in an origin trial on your site simply by registering a token for your origin, and not for the script.

Third-party scripts need to use tokens with third-party matching enabled, injected via the script itself (not included in a meta tag or header on your site) using code like the following:

function addTrialToken(tokenContents) {
  const tokenElement = document.createElement('meta');
  tokenElement.httpEquiv = 'origin-trial';
  tokenElement.content = tokenContents;
  document.head.appendChild(tokenElement);
}

# Third-party token is provided via an external script, not a meta tag, HTTP header or inline script

Third-party tokens are validated against the origin of the script that injected them, but inline scripts and <meta> tags in static markup do not have an origin (i.e. a source URL).

This means that a third-party token must be provided via an external script, not in a <meta> tag or inline script. It doesn't matter if the external script that injects the token comes from the same origin as the containing page, or a different origin, as long as the origin of the script matches an origin registered for the trial.

You can see a demo of this at ot-iframe-3p.glitch.me.

# Origin trial feature access is supported for the method used to provide a trial token

Some types of access to origin trial features require you to provide a trial token in a specific way. For example, the only way to enable origin trial access for service workers and shared workers is to provide a token in an Origin-Trial header.

# Subdomain matching is enabled for a token used on a subdomain

If an origin trial feature doesn't seem to be working for some pages on your site, check that tokens are correctly set up for the subdomains serving them.

When you register for an origin trial, you can optionally choose to match all subdomains of the origin:

You can also match subdomains for third-party tokens:

Subdomain tokens will not be issued for origins in the Public Suffix List. For example, you cannot register an origin such as https://appspot.com or https://github.io, though you can register for domains within that origin, such as https://example.appspot.com or https://example.github.io.

# The token is still valid

Tokens are valid for six weeks after they're created. Beyond that, you must submit feedback in order to extend the Valid Until date. Origin Trials Guide for Web Developers explains how to make sure your token is valid for an entire origin trial.

You can check for active tokens on your Chrome Origin Trials My Registrations page:

Chrome DevTools displays Status Success if the token is still valid:

If your token has expired, DevTools will display the status Expired and your My Registrations page will display an Expired Tokens section.

# The origin trial hasn't ended

You can check the end date for an origin trial from its registration page:

For trials that have ended, DevTools will display something like this:

You will be sent automated emails when feedback is required or a token is about to expire, though not when the trial ends.

# The origin trial is available for the current user

Some origin trials are unavailable to certain users, even if a valid token is provided.

If a trial isn't available for the current user, Chrome DevTools will display a TrialNotAllowed warning:

Information about usage restrictions and availability will be provided for each origin trial.

As with any web platform feature, you should use feature detection to confirm that an origin trial feature is supported before you use it.

# Origin trial usage restrictions haven't been exceeded

By default, an origin trial feature will be enabled on any page that has a valid token for the trial.

However, except in rare cases, origin trial usage is limited to a maximum of 0.5% of all Chrome page loads. The origin trial feature will be disabled if total usage by all Chrome users exceeds that amount. DevTools will show the token status as disabled.

Some trials also provide an option to limit usage, which means origin trial features will be disabled for some users. This option is made available from the registration page for an origin trial that offers it:

If you're noticing that access by your users to an origin trial feature is lower than expected, make sure that 'Standard Limit' is selected.

# Iframes provide their own tokens

To allow access to an origin trial feature, an iframe must provide a token in a meta tag, an HTTP header, or programmatically. Iframes don't inherit access to features enabled for pages that contain them.

ot-iframe.glitch.me demonstrates access to an origin trial feature from an iframe. ot-iframe-3p.glitch.me provides multiple cross-origin iframe examples.

# Permissions policies are correctly configured

Some origin trial features may be affected by a Permissions-Policy header (previously known as a Feature-Policy header). You can check for this in the Intent to Experiment for the trial feature, or in developer documentation for the feature on web.dev or developer.chrome.com/blog.

Make sure the feature you are attempting to access is not blocked by a Permissions-Policy directive. You can check for response headers in the Chrome DevTools Network panel, and view the full list of allowed features in the Application panel.

# What about the workers?

Origin trials features can be made available to service workers, shared workers, and dedicated workers. However, the only way to enable access for service workers and shared workers is to provide a token in an Origin-Trial header.

Dedicated workers inherit access to features enabled by their parent document.

# Token is provided before feature is accessed

Make sure that an origin trial token is provided before a trial feature is accessed. For example, if a page provides a token via JavaScript, make sure the code to provide the token is run before code that attempts to access the trial feature.

# Origin trial demos

• Token in a meta tag
• Token in a header
• Feature accessed in an iframe
• Token injected by third-party script
• ot-iframe-3p.glitch.me: cross-origin iframe examples

# Find out more

• Get started with Chrome's origin trials
• Third-party origin trials
• Origin trials guide for web developers
• Origin trial explainer
• Running an origin trial
• Process for launching new features in Chromium
• Intent to explain: Demystifying the Blink shipping process
• Use Origin Trials in Microsoft Edge
• Origin trials for Firefox