Version 100 of Chrome, Firefox, and Edge is on the way.
User-Agent (UA) is a string that browsers send in HTTP headers, according to Google. It enables servers to recognise the user's browser. The UA reports a three-digit version number instead of a two-digit number when a browser reaches version 100. According to Google, web developers parse these strings using a variety of techniques. That is the crux of the issue.
On its developer site, Google provided a helpful explanation of the potential issues:
Different browsers have different formats for the User-Agent string, and site-specific User-Agent parsing, because there is no single specification to follow. Some parsing libraries may have hard-coded assumptions or bugs that don't take three-digit major version numbers into account.
The good news is that when browsers switched to two-digit versions, many libraries improved their parsing logic. As a result, three-digit version numbers should no longer be an issue. However, Chrome developers have been conducting field tests that have revealed issues that need to be addressed. It's now a race against time.
Google and Microsoft are currently planning to release Chrome 100 and Edge 100 on March 29th, 2022. Meanwhile, Mozilla has set May 3rd, 2022 as the release date for Firefox version 100. All three companies are conducting tests and addressing issues in order to make their rollouts as seamless as possible. To date, the teams have discovered flaws on Yahoo, Bethesda, T-Mobile, and HBO Go, among other popular websites.
Keeping disaster at bay
Some of the issues discovered by the developers have already been addressed. Others will almost certainly be addressed before the rollouts in the coming weeks. However, there will undoubtedly be bugs that the developers will not be able to fix before the release of the respective version 100.
Google and Mozilla both have backup plans in case the internet goes down.
The backup plan for Chrome, according to Google, is to use a flag to freeze the major version number at 99. The real major version number will then appear in the UA string's minor version part. Of course, the three-digit number in the minor version part of the string could cause problems as well, which is why Google is also testing its backup plan.
When it comes to bug fixes after the launch, Mozilla will take a different approach. Mozilla's approach will be determined by the severity of the problem. With its site interventions mechanism, Mozilla can quickly fix broken websites. For widespread issues, you can also freeze the major version number in Firefox.
