Hospitals, financial institutions, and manufacturing plants often rely on internal web apps that use or Microsoft Silverlight . When Mozilla removed NPAPI support in Firefox 53, these applications broke. Organizations deliberately stay on Firefox 52.9.0 ESR to keep these mission-critical systems running while they slowly transition to modern alternatives.
While standard Firefox versions update every few weeks, the is designed for organizations like schools and businesses that need stability over new features. firefox version 52.9. 0 esr download