Firefox developer Mozilla is warning users that when its browser – and when Google’s Chrome browser – reaches version 100, major websites will likely not identify the browsers properly, possibly not working properly as a result.
Firefox currently sits at version 97, while Chrome is currently showing version 98. Once those are updated to version numbers with triple digits, Mozilla says users could experience inconsistent problems across an unpredictable range of websites.
Mozilla explains that website servers examine what’s called the User-Agent in order to determine which browser is being used. They then use that information to configure sites so that they display correctly.
Why can a three-digit version number be problematic?
When browsers first reached version 10 a little over 12 years ago, many issues were discovered with User-Agent parsing libraries as the major version number went from one digit to two.
Without a single specification to follow, different browsers have different formats for the User-Agent string, and site-specific User-Agent parsing. It’s possible that some parsing libraries may have hard-coded assumptions or bugs that don’t take into account three-digit major version numbers. Many libraries improved the parsing logic when browsers moved to two-digit version numbers, so hitting the three-digit milestone is expected to cause fewer problems. Mike Taylor, an engineer on the Chrome team, has done a survey of common UA parsing libraries which didn’t uncover any issues. Running Chrome experiments in the field has surfaced some issues, which are being worked on.
What are browsers doing about it?
Both Firefox and Chrome have been running experiments where current versions of the browser report being at major version 100 in order to detect possible website breakage. This has led to a few reported issues, some of which have already been fixed. These experiments will continue to run until the release of version 100.
There are also backup mitigation strategies in place, in case version 100 release to stable channels causes more damage to websites than anticipated.
Firefox and Chrome developers are reportedly running experiments, logging issues that are encountered. Currently, the list of sites reporting bugs with a version 100 includes T-Mobile, Yahoo, and Daimler.
“If the breakage is widespread and individual site interventions become unmanageable,” continues the blog post, “Mozilla can temporarily freeze Firefox’s major version at 99 and then test other options.”
Developers working on Google Chrome also have a “backup plan to use a flag to freeze the major version at 99.”
(Via AppleInsider)