We had to update our enterprise app and we are having a lot of problems on iOS 9. I am facing two scenarios.
1) When we first try to install we get the standard ambiguous Unable to Download App error message.
2) I thought it may be a profile issue but we get passed this on some devices and get the Untrusted Enterprise Developer alert. However going to Settings -> General there is no Profiles row to tap so it's not possible to trust the app.
Has anyone else faced these issues?
The unable to download app error is often a bad IPA link in the .plist file. Verify that you can install the app on a device running an earlier version of iOS. Also, starting with iOS 8, I believe, the link to the IPA must be secure (i.e. use https).
The profile will not show up in the list of profiles until the app has been installed. If you can't download the app, it can't be installed, and the installation of the app also includes installing the provisioning profile.
To get more information, try the download while the device is plugged into your mac and look at the devices console to get more details. For how to bring up the console, look here: https://stackoverflow.com/a/30992454/3708242 Make sure you are looking at the device console, not the device logs
