How do you troubleshoot a web application that works in one browser but not another?

To troubleshoot a web application that works in one browser but not another, start by checking for browser-specific issues such as compatibility with HTML, CSS, or JavaScript. Ensure that the web application is using standardized code and features supported by all major browsers. Use browser developer tools to debug and identify any errors or warnings specific to the problematic browser. Consider using polyfills or alternative solutions for browser-specific issues. Test the application in multiple browsers to ensure cross-browser compatibility and make any necessary adjustments to the code to resolve the issue.