Adobe Acrobat Reader 9 is a legacy version of the software, originally released in . Because Adobe officially ended support for this version on June 26, 2013

Historically, Adobe hosted all old readers on an FTP server. That FTP is now closed, but some mirror sites have preserved the files. Look for a file that matches this pattern: ftp.adobe.com/pub/adobe/reader/win/9.x/9.5.5/enu/AdbeRdr955_en_US.exe

Using Adobe Reader 9 on a modern, internet-connected computer is not recommended Adobe Help Center Vulnerability:

Instead, users should download the latest version of (Document Cloud). The modern version offers:

The first version of Adobe Acrobat Reader, introduced in 1993, was a groundbreaking tool that allowed users to view and print Portable Document Format (PDF) files. Over the years, Adobe continued to update and improve the software, adding new features and enhancing its performance. By the mid-2000s, Adobe Acrobat Reader had become an industry standard for viewing and managing PDF documents.