Deprecations and removals in Chrome 104

Chrome 104 beta was released on June 23, 2022 and is expected to become the stable version in early August, 2022.

# Block third-party contexts navigating to filesystem URLs

iframes can no longer navigate to filesystem URLs. Top frame support for navigating to filesystem URLs was dropped in Chrome 68.

# Remove non-standard client hint mode

Four client hints (dpr, width, viewport-width, and device-memory) have a default allowlist of self but behave as though they have a default allowlist of * on Android, contrary to the spec. This is now fixed, increasing privacy on Android by requiring explicit delegation of these hints.

# Remove U2F API (cryptotoken)

Chrome's legacy U2F API for interacting with security keys is no longer supported. U2F security keys themselves are not deprecated and will continue to work.

Affected sites should migrate to the Web Authentication API. Credentials that were originally registered via the U2F API can be challenged via web authentication. USB security keys that are supported by the U2F API are also supported by the Web Authentication API.

U2F is Chrome's original security key API. It allows sites to register public key credentials on USB security keys and challenge them for building phishing-resistant two-factor authentication systems. U2F never became an open web standard and was subsumed by the Web Authentication API (launched in Chrome 67). Chrome never directly supported the FIDO U2F JavaScript API, but rather shipped a component extension called cryptotoken, which exposes an equivalent chrome.runtime.sendMessage() method. U2F and Cryptotoken are firmly in maintenance mode and have encouraged sites to migrate to the Web Authentication API for the last two years.

# Deprecation policy

To keep the platform healthy, we sometimes remove APIs from the Web Platform which have run their course. There can be many reasons why we would remove an API, such as:

• They are superseded by newer APIs.
• They are updated to reflect changes to specifications to bring alignment and consistency with other browsers.
• They are early experiments that never came to fruition in other browsers and thus can increase the burden of support for web developers.

Some of these changes will have an effect on a very small number of sites. To mitigate issues ahead of time, we try to give developers advanced notice so they can make the required changes to keep their sites running.

Chrome currently has a process for deprecations and removals of API's, essentially:

• Announce on the blink-dev mailing list.
• Set warnings and give time scales in the Chrome DevTools Console when usage is detected on the page.
• Wait, monitor, and then remove the feature as usage drops.

You can find a list of all deprecated features on chromestatus.com using the deprecated filter and removed features by applying the removed filter. We will also try to summarize some of the changes, reasoning, and migration paths in these posts.