Hello, Try opening in [[Troubleshoot Firefox issues using Safe Mode|Firefox Safe Mode]] and see if the browser closes properly after opening in that. Safe mode is a troubleshooting mode that turns off some settings, disables most add-ons (extensions and themes). Since Firefox has trouble closing, make sure that it is not running in your Task Manager before opening in Safe Mode. If Firefox is not running, you can start Firefox in Safe Mode as follows: * On Windows: Hold the '''Shift''' key when you open the Firefox desktop or Start menu shortcut. When the Firefox Safe Mode window appears, select "Start in Safe Mode".<br> [[Image:Safe Mode Fx 15 - Win]] ''To exit Firefox Safe Mode, just close Firefox and wait a few seconds.'' '''''If the issue is not present in Firefox Safe Mode''''', your problem is probably caused by an extension, and you need to figure out which one. Please follow the [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems]] article to find the cause. When you figure out what's causing your issues, please let us know. It might help others with the same problem.