Package file is invalid when trying to load Facebook When I try to load the Facebook app on my new Samsung Galaxy S3, I get an error of Package File is Invalid. I have been able to load other apps via Google Play store. Facebook seems to be the only one I'm having trouble with.
This error has been noticed recently. The other day, I was trying to update the Samsung Push app, but it kept on failing. So, I just kept trying to update it, despite the frustrations. Eventually, it updated successfully.

Maybe it's just a Google Play issue.

Update 2013-08-13: From Al's comments, Google has officially recognized this issue, as is in fact listed in Google Support.


  We’ve received reports that some users are getting "Package File
  Invalid" while trying to download or update apps.
  
  We’re currently investigating a permanent solution, and there are no
  workarounds at this time.
  
  We’ll continue to update this page with developments, so check back
  soon.


EDIT #1: Oops, looks like my UPDATE has been mentioned in bmdixon's answer already.

UPDATE 2013-08-15: As of this time, Google has already fixed the issue. Source.