I have a 2013 SharePoint hosted app. I made some changes and went through the update process (changed the app version, kept the id the same, uploaded the package to the app catalog and updated the app immediately through the site contents of the site collection). Everything worked fine. However, when I go through the same process again with an even higher version, the app says that it's updating and after completion everything is the same. In fact, the app even shows that a new version is available. If I click "Get It", it says that it's updating for about 5 to 10 minutes and then nothing changes, same old app, same old files, same old version number, still says that a newer version is available. In Central Admin. I started to monitor the app and found that there were failed upgrades with an error message of "There was a problem accessing the file system on the server."
Any help or pointers are greatly appreciated, of course. Thank you.