I manage a couple sites that like to use pdf’s for menus. Each time the menu changes, they upload a new pdf with a new file name. Now first, I always recommend using webpages instead of PDF’s. Google can’t read PDF’s. (At least not yet. With Google, there is no telling what they will be able to do.) Since Google can’t read PDF’s, all that great content on your PDF is completely invisible to them. With WordPress, it’s easy to make changes to prices and menu options, so there isn’t really a need to use PDF’s, but if you must…
Please keep the same file name for your PDF’s. When Google indexes your site, they track all your url’s – even for your PDF’s. So, if you delete a PDF, that url now gives an error. (Yes, you could keep all your PDF’s forever and never take them down, but who really wants a site that big and to pay for all that storage?) Using this method, you will also save yourself from having to change the links on your page to the new file name, which will save you time.
Two things to remember when doing this:
1) You must delete the old file before uploading the new one. If you don’t, WordPress will simply append a number to the end of the file name to keep the two files from getting mixed up. That means a different url!
2) Since you aren’t changing the file name, your browser will assume you are looking for the same file and display the old pdf from it’s cache. You will have to refresh or possibly even a hard refresh to see your new file. (Hard refresh is Ctrl + F5) If you are looking for a way to easily distinguish between the files once you upload them to make sure the right version is showing, I recommend a tiny V1, V2, V3, etc in the bottom corner.
3) If your PDF file name is currently being proceeded by the year and month, you will need to go into SETTINGS > MEDIA and uncheck the box that says “Organize my uploads into month- and year-based folders”, otherwise, this will not work. If the files you already are using have the year and month, you will need to uncheck that box, and then delete the old files and re-save the new way for this to work.
This all sounds like a small thing, but it can prevent Google crawl errors on your site – which can cause quite a lot of problems. We want to make Google happy!
One last tip: If you are using Google Webmaster Tools and are already seeing quite a few crawl errors on your site, use the Redirection plugin to redirect those url’s to their new location.
Read more of my SEO tips here: http://wpdecoder.com/wordpress/seo/