When you upgrade to the latest version of Firefox, a compatibility check is performed to determine which plugins either are or aren't compatible with the latest version. The responsibility for a plugin's compatibility with current Firefox versions is the company's itself, Real Networks is responsible for releasing updated versions of the plugin that are compatible with the current version of Firefox. '' Troubleshooting & using Real Player Plugin with Firefox'' [https://support.mozilla.com/en-US/kb/Using%20the%20RealPlayer%20plugin%20with%20Firefox] ''You can also use Mozilla's PluginDoc for additional troubleshooting steps and information.'' [http://plugindoc.mozdev.org/] Real Player Support [https://real.custhelp.com/app/answers/detail/a_id/8883/session/L3RpbWUvMTMyMjQzMTI2Ny9zaWQveWhUOVFiS2s%3D] '