Deprecations and removals in Chrome 84
Chrome expects to start the spec-mandated turn down of AppCache in Chrome 85. For details and instructions for managing the transition gracefully, see Preparing for AppCache removal. For information on a feature that will help you identify uses of this and other deprecated APIs, see Know your code health
@import rules in CSSStyleSheet.replace() removed
The original spec for constructable stylesheets allowed for calls to:
This use case is being removed. Calls to
replace() now throw an exception if
@import rules are found in the replaced content.
Remove TLS 1.0 and TLS 1.1
TLS (Transport Layer Security) is the protocol which secures HTTPS. It has a long history stretching back to the nearly twenty-year-old TLS 1.0 and its even older predecessor, SSL. Both TLS 1.0 and 1.1 have a number of weaknesses.
- TLS 1.0 and 1.1 use MD5 and SHA-1, both weak hashes, in the transcript hash for the Finished message.
- TLS 1.0 and 1.1 use MD5 and SHA-1 in the server signature. (Note: this is not the signature in the certificate.)
- TLS 1.0 and 1.1 only support RC4 and CBC ciphers. RC4 is broken and has since been removed. TLS’s CBC mode construction is flawed and is vulnerable to attacks.
- TLS 1.0’s CBC ciphers additionally construct their initialization vectors incorrectly.
- TLS 1.0 is no longer PCI-DSS compliant.
Supporting TLS 1.2 is a prerequisite to avoiding the above problems. The TLS working group has deprecated TLS 1.0 and 1.1. Chrome has now also deprecated these protocols.
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- They are superseded by newer APIs.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.