Adobe no longer supports their PDF reader on Linux and the official page does not offer it for download. \
However, some files may not display properly on Ubuntu's default PDF reader Evince or PDF forms may not work as expected. Hence, you may still need to use it.

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

Here is how to install the Adobe Reader (acroread) if you need to:

1. Download the .deb archive from the Adobe servers (yes, it's still there):

   cd /tmp && wget http://ardownload.adobe.com/pub/adobe/reader/unix/9.x/9.5.5/enu/AdbeRdr9.5.5-1_i386linux_enu.deb
   

2. Install required dependencies first:

   sudo apt-get install libgtk2.0-0:i386 libnss3-1d:i386 libnspr4-0d:i386 lib32nss-mdns libxml2:i386 libxslt1.1:i386 libstdc++6:i386
   

3. Install the downloaded .deb file:

   sudo dpkg -i AdbeRdr9.5.5-1_i386linux_enu.deb
   

The above instructions worked for me on a 64 bit Ubuntu 14.04.