If You have been unable to actually open PDF documents. Adobe Reader software don't open air.pdf until now because it is either not a supported file type or because the file was damaged (for example, it was sent as an email attachment and decoded correctly. Was not done). These documents come from all different sources - you haven't had any problems with any of them in the past.
This message is usually a good sign that there is something wrong with your PDF files. How does someone open these files? How did you get these files?
If these are files that you have saved from within the browser, do not use the browser's save or page functionality, instead, when the PDF file is shown inside the browser, move the mouse cursor to the lower center of the browser Go.
If you cannot open a PDF on your computer, try the suggestions below within the order they appear.
1. Install free Adobe Acrobat Reader DC on your PC.
2. If you've got Acrobat Reader DC or Acrobat DC installed on your computer, skip to the next step.
3. Acrobat Reader DC is the only free PDF viewer that will open and interact with all kinds of PDF content - including forms and multimedia.
Go to the Adobe Acrobat Reader download page, then click Install Now. For step-by-step follow instructions
Update Acrobat Reader DC or Acrobat DC
Open Acrobat Reader DC or Acrobat DC