Sometimes it feels like a remote issue and sometimes it feels like a lot of users face this problem after every iOS upgrade. If you are unable to purchase (or download) apps from the App Store on your iPhone or iPad after upgrading or updating your iOS firmware (iOS 7.0.x), you're not alone.
And it's not a severe issue in most cases. It's mostly something to do with a reset in iTunes & App Store account configurations. Here are some things you should try:
The first thing you're going to try is sign out of all your accounts from Settings -> iTunes & App Store. Tap on the Account field in that page and then tap on Sign out. This will sign you out of your Apple ID (but not out of iCloud).
Now, don't sign in here. Head back to the App Store and download any app. When it prompts for an account ID and password, enter them. Hopefully, this should solve the issue.
2. Reset All Settings
If that didn't work, try resetting all settings (but do not Erase All Data). Just reset the settings. This will effectively make your iPhone startup as new but you will have all the old data intact. You will have to enter all your passwords again. That's a pain but go through it and it might solve the purchase issue.
To reset: Settings -> General -> Reset -> Reset All Settings.
3. Try Through the Computer
The other thing you can try is to download an app via iTunes on your Mac/PC. Then sync your iPhone or iPad to the Mac/PC through iTunes – which will install the app on your iPhone/iPad. To do this:
- Look for the app on iTunes and install it
- After it downloads to iTunes, connect your iPhone or iPad to the computer
- Sync the iPhone/iPad to iTunes
- Did the app get installed?
4. Backup & Restore
Well, if nothing else works, this is the standard remedy. But you could talk to Apple Care execs before you decide to do a complete restore. Some users have pointed out that Purchasing apps hits a roadblock after iOS 7.0.4 so if you just upgraded to this version and aren't able to download apps, try the methods.