Could you provide a screenshot of the error? Can you uninstall from the play store and install again?

I have the same problem. Have tried standard fix (turn off auto-restore, delete cache and data of Google Play and Google Play Services, uninstall their updates, reboot).

Circumstances: installed beta update for Firefox. Found it was slow and locking up, so I uninstalled it. When I attempted to reinstall the stable version, I got the package file is invalid error. After several attempts and then trying the standard fix, I tried reinstalling the beta version. Same error.

This is on a Verizon Samsung Galaxy Note II SCH-I605

Please advise.

Okay. This is crazy. I wanted to make certain that Google Play could download and install other apps without the error. I chose a large game "The Secret Society". It downloaded and installed fine. I uninstalled it.

Then I attempted to install Firefox again, preparing to capture a screen shot of the error for posting here, but it installed without a hitch this time.

Not sure if the passage of time, a correction on the server side, or the mere act of downloading, installing and uninstalling another app did the trick, but I'm glad I'm back in business now. I hate it when that happens!

Clear the google play cache.

1. Visit Settings > Apps on your device
2. View All apps
3. Select the Google Play store app, and then tap Clear data and Clear cache.
4. Then, select Download manager and tap Clear data and Clear cache.