Mozilla has launched an experiment in which they change the user agent of the Firefox browser to a three-digit “Firefox / 100.0” version to see if it breaks websites.
A user agent is a string used by a web browser that includes information about the software, including its name, version, and technologies it uses.
When a new version of a browser is released, developers also increment the version number in the user agent string.
For example, the current user agent for Mozilla Firefox version 90 is listed below.
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0
Please note that if you have the privacy of Firefox.
For Google Chrome 92, the current user agent is:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36
When visiting a website, user agent strings are sent to a website so that the site knows the software capabilities of the visitor. This information allows the website to modify its response to take into account the different characteristics of the browsers.
Testing if the Firefox 100 user agent breaks websites
As Firefox version numbers are currently in double digits, Mozilla developers are investigating if something goes wrong when they release version 100 of Firefox Nightly in March 2022.
“We would like to run an experiment to test whether a UA string with a three-digit Firefox version number will break a lot of sites,” Mozilla Personnel Engineering Program Manager Chris Peterson said in a Error message first seen by Techdows.
“This new storm
general.useragent.experiment.firefoxVersion pref can override the Firefox version of the string UA “.
When testing, a registered Firefox user will change their user agent to the next string in the hope that if something breaks, they will report it to Mozilla.
Mozilla/5.0 (Windows NT 10.0; rv:100.0) Gecko/20100101 Firefox/100.0
Peterson said that he has been testing the browser with a “Firefox / 100.0” user agent string for about four months and has only encountered a problem using Slack.
“I found that Slack message pop-up menu buttons (like ‘Add reaction’ or ‘Reply in thread’) stop working for Firefox versions> = 100 and = 520,” explained Peterson.
In this case, the problem appears to be a bug with Slack when comparing version numbers that are strings rather than numbers (integers). While Slack quickly fixed this problem, it illustrates how simple coding errors can produce unexpected results when the user agent switches to version 100.
If continuous testing shows that many sites are corrupted by the new user agent, Firefox can freeze the user agent to a two-digit number such as “Firefox / 99.0”.
For those who want to test the next user agent change on their own sites or sites they visit frequently, you can manually change your user agent string by following these steps:
- Open Firefox, enter about: config in the address bar and press Enterokay.
- Look for general.useragent.override.
- When it appears, select ‘String’ and then click the plus sign (+), as shown in the image below.
- After clicking the + icon, a field should open where you need to enter the text: Mozilla / 5.0 (Windows NT 10.0; rv: 100.0) Gecko / 20100101 Firefox / 100.0 As shown below.
- Then click the check mark button to save the settings.
- You can close the about: config tab.
As long as this setting is in place, the browser will send the new user agent string to websites. If you have a problem with the websites you visit, you should create a new bug report for Mozilla.
To change your user agent back to its original string, simply go back about: config and search general.useragent.override adjust again.
When it appears, click the trash can icon to delete the configured settings.