Mozilla warns Chrome, Firefox ‘100’ person brokers could break websites
Mozilla is warning web site builders that the upcoming Firefox 100 and Chrome 100 variations could break web sites when parsing user-agent strings containing three-digit model numbers.
A user-agent is a string utilized by an online browser that features details about the software program, such because the browser identify, its model quantity, and the assorted applied sciences it makes use of.
When an individual visits a web site, the browser’s user-agent is shipped together with the request for an online web page. This enables the online web page to test the customer’s browser model and modify its response primarily based on the options the browser helps.
For instance, the present user-agent for Mozilla Firefox model 97 is:
Mozilla/5.0 (Home windows NT 10.0; Win64; x64; rv:97.0) Gecko/20100101 Firefox/97.0Be aware, you probably have the Firefox ‘privateness.
For the present model of Google Chrome 98, the user-agent is:
Mozilla/5.0 (Home windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.82 Safari/537.36Mozilla warns of model 100 user-agent strings
In August 2021, Mozilla launched an experiment to see if the three-digit ‘Firefox / 100’ user-agent string would trigger issues with web sites. Google quickly adopted with their very own experiment for Chrome 100.
In each experiments, Mozilla and Google discovered a small variety of web sites that will not function accurately when parsing a user-agent string that contained a three-digit model quantity.
Since then, Mozilla has been protecting observe of internet bugs attributable to the model 100 change and has discovered issues on web sites for HBO Go, Bethesda, Yahoo, Slackand these created by the Duda web site builder.
For essentially the most half, these points have ranged from the web sites stating the browser is unsupported to person interface points affecting parts of the positioning.
“With out a single specification to observe, completely different browsers have completely different codecs for the Consumer-Agent string, and site-specific Consumer-Agent parsing. It’s potential that some parsing libraries could have hard-coded assumptions or bugs that don’t bear in mind three-digit main model numbers, “Mozilla explains in a brand new weblog submit concerning the upcoming user-agent adjustments.
“Many libraries improved the parsing logic when browsers moved to two-digit model numbers, so hitting the three-digit milestone is predicted to trigger fewer issues.”
Mozilla and Google will proceed operating experiments for model 100 user-agents till the browsers are launched on March 29 for Chrome and Might 3 for Firefox.
If there are points with websites that Mozilla or Google can’t repair earlier than these variations are launched, each Google and Mozilla have backup plans prepared to make sure the websites usually are not affected.
For Firefox, Mozilla has a website interventions mechanism to freeze the user-agent at Firefox / 99 or inject CSS or different overrides to repair the bugs.
Equally, Chrome plans to freeze the model proven within the user-agent string to 99 for problematic websites and report the precise model in one other a part of the user-agent string.
As for web site builders and admins, Mozilla asks them to check if altering to the Firefox 100 and Chrome 100 user-agents break their web sites.
This may be performed by performing the next steps:
Configure Firefox Nightly to report the key model as 100
- Open Firefox Nightly’s Settings menu.
- Seek for “Firefox 100” after which test the “Firefox 100 Consumer-Agent String” possibility.
When enabled, the Firefox user-agent string will change to:
Mozilla/5.0 (Home windows NT 10.0; Win64; x64; rv:100.0) Gecko/20100101 Firefox/100.0Configure Chrome to report the key model as 100
- Go to chrome: // flags / # force-major-version-to-100
- Set the choice to `Enabled`.
When enabled, the Chrome user-agent string will change to:
Mozilla/5.0 (Home windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4758.102 Safari/537.36If an issue is discovered, Mozilla asks builders to file a report on webcompat.com so that there’s ample time to handle any points.