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Content such as images and PDFs is often stored, or cached, locally, so that web content displays more quickly. So when you make changes to your website, you may not see the new version right away. The vagaries of caching are described here: As soon as you post anything to the web, it is cached a bunch of places, which you may or may not have control over.

Caching is good. Without it, the web would be impossibly slow. That’s why news outlets and most of the rest of the internet use content delivery networks.

You have a couple of caches on your computer. Processwire and Wordpress have some. CHCS and the hosting companies we use have some. Social media have their own (which is why you may get different results from Facebook and LinkedIn). And anything you post will probably end up in the Wayback Machine on Want to see what your site looked like a year ago? They probably have it.

Think live radio. Once the broadcast goes out, if the producer recorded it, they can edit it for future use. But they cannot change any recordings someone may have made of the original broadcast.

So if you know that a document you post is likely to change, do not link directly to it. Instead, make a page on your site that you can share with others, like On that page, make a link that looks like

My Document (version 1)

If you need to change it, give it a different name, like my-document-v2.pdf, and change the link to

My Document (version 2)

This works because caches generally expect HTML (web) pages to change, and they are set to expire in a certain period of time, generally something like three hours, so they check for a new version of that web page after that time. But caches assume that documents like PDFs never change. Which is why you need to give your PDF a different file name you change it, and give it a different link (and delete the old version). This way, the various caches will see the new version of fairly quickly, note that its content has changed, and pull in the new document with a new name, like

Of course, you can get around the issue by never changing your original PDF. But nobody’s perfect, right?

After you make changes to your website, if you don't see the new version, check one or more of the following.

  1. Make sure that you have saved your changes.
  2. Preview the changes.
  3. Do a "hard refresh" of the page you have changed.
    1. On Windows, press Ctrl+F5.
    2. On Safari on Mac, go to Safari > Empty Cache, or press Opt + ⌘ Cmd + E.
    3. On other Mac browsers, press Cmd+Shift+R.
  4. View your page in a Private Window or Incognito Window (the name depends on the browser you are using).
  5. Clear your browser's cache. See instructions at
  6. View your page in a different browser, preferably one that you have not previously used to visit the page you are viewing.
  7. View your page on a different computer, or on a phone or tablet.
  8. You may have a router or modem that needs to have a cache cleared. Please check with your network administrator or internet service provider on how to do this.
  9. View your page on a computer on a different network.
  10. View your page from a different location.