Disable Built-in PDF Viewer (PDF.js)

Supported on: Firefox 60 or later, Firefox 60 ESR or later

Registry

HKLM Software\Policies\Mozilla\Firefox

HKCU Software\Policies\Mozilla\Firefox

Value name: DisableBuiltinPDFViewer

Enabled: DisableBuiltinPDFViewer = 1

Disabled: DisableBuiltinPDFViewer = 0

Description

If this policy is enabled, PDF files are not viewed within Firefox. If this policy is disabled or not configured, PDF files are viewed within Firefox.