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# Defect Severity
## Definition
We use the `severity` field in Bugzilla to indicate the scope of a
bug's effect on Firefox.
The field is display alongside the bug's priority.
## Values
Severity levels and their definitions are enumerated at <https://wiki.mozilla.org/BMO/UserGuide/BugFields#bug_severity>.
By default, new bugs have a severity of `--`.
### Examples of S1 bugs
- WebExtensions disabled for all users
- Web search not working from URL bar
- Crashes with data loss
### Examples of S2 bugs
Bugs that could reasonably be expected to cause a Firefox user to switch browsers,
either because the severity is bad enough, or the frequency of occurrence is high enough.
indefinitely in a onResize loop
Reddit's comment section JS code makes selecting text slow on Nightly
Bugs involving contractual partners (if not an S1)
Bugs reported from QA
important message is not visible with the dark theme. It's not marked as S1 since the
issue is reproducible only on one OS and the functionality is not affected.
are not working on several sites with ETP on (default). This is not an S1 since turning
ETP off fixes the issue.
Fuzzblocker bugs, which prevent fuzzing from making progress
### Examples of S3 bugs
Bugs filed by contributors as part of daily refactoring and maintenance of the code base.
[Bug 1634171](https://bugzilla.mozilla.org/show_bug.cgi?id=1634171) - Visual artifacts around circular images
Bugs reported from QA
the associated steps to reproduce are uncommon,
and the issue is no longer reproducible after refresh.
reproducible only on a specific web app, and only with a particular set of configurations.
## Rules of thumb
- The severity of most bugs of type `task` and `enhancement` will be
`N/A`
- **Do not** assign bugs of type `defect` the severity `N/A`