title: Google Chrome Cache PDF files
body: <p>I have built a small PHP/MySQL internal app to host and sort documents. All works perfectly until it comes to updating a file, in this case a .PDF file. When a user updates the .PDF the new file is on the server as expected and the older version deleted. A user is getting the new version providing they never opened the old version. </p>
  
  <p>Now the problem.... If a user has opened the older version of the .PDF at some point in the past they do not get the newer version when a link is clicked to view the document even though its only the new version actually physically on the server. </p>
  
  <p>I'm guessing that Google Chrome Browser is caching the older version of the PDF somewhere. How can I get around this? Due to the amount of users and the number of times a day some of the documents are updated asking users to manually clear any cache is not practical.</p>