Someone has reported a bug. The issue is now in the needs triage list. You can help!
Triaging is an important step in the process. You will be assessing the quality of the issue. You will notice right away that a lot of issues are either invalid or lack the minimum details for being able to investigate and create a diagnosis.
For having a better understanding of the issue, you will probably need to have a setup which makes it possible to have a fresh profile of the browser you are testing with. For example, on Firefox you can create a profile which resets each time the browser restarts.
Reproducing the issue is sometimes a very tough game. Some issues are happening because of the local settings of the person who created the report. Geographical location, preferences choices, web extensions and add-ons, OS, network constraints, logged on the services, devices and many other parameters are all possibly the source of the breakage as perceived by the reporter.
Try your best to understand the report and reproduce the issue. If you have a doubt, reach out someone from the project to help. You may wish to add a screenshot if one was not provided, or if you are seeing different results from the one that was provided. Think of yourself another bug reporter.
If you can not reproduce the issue, check if it has been opened by an identified reporter or anonymously. If the issue has an identified reporter, you may want to ask them additional questions (give them a week or two to answer before closing the issue). If the issue was reported anonymously, do not hesitate to close with one of the statuses below. Please do not forget to thank the reporter for opening the issue in the first place.
When closing, give information on the rationale for your decision. It doesn't have to be long, but that will help if we decide to reopen or for the reporters to understand the reasoning.
If you can reproduce the issue: