The default Android external SD file structure
You should have a default structure used by Media Scanner to collect data present on your system, that gets stored on a database, allowing it to keep track of all the media content present on the device:
Music/ - Media scanner classifies all media found here as user music.
Podcasts/ - Media scanner classifies all media found here as a podcast.
Ringtones/ - Media scanner classifies all media found here as a ringtone.
Alarms/ - Media scanner classifies all media found here as an alarm sound.
Notifications/ - Media scanner classifies all media found here as a notification sound.
Pictures/ - All photos (excluding those taken with the camera).
Movies/ - All movies (excluding those taken with the camcorder).
Download/ - Miscellaneous downloads
Adittionaly, when taking screenshots, by default the folder used is:
The media scanner service
When your device boot's up, the media scanner service is launched and runs through the entire external storage to find if there is any new media content.
If new media is found:
- It adds an entry of that media content into the content database
Each entry in the content database contains the media meta-data (name, date, file size, etc...)
When changes are made to a media content, the database needs to be updated, otherwise, third party applications will not be able to access that particular media content.
Applications make use of the public class MediaScannerConnection, as to "force" Media Scanner to perform an instant scan. That's with applications like Instant Upload are able to work properly.
MediaScannerConnection provides a way for applications to pass a newly created or downloaded media file to the media scanner service. The media scanner service will read metadata from the file and add the file to the media content provider. The MediaScannerConnectionClient provides an interface for the media scanner service to return the Uri for a newly scanned file to the client of the MediaScannerConnection class.
With Instant Upload enabled, photos and videos taken with your phone are automatically uploaded to a private album on Google+.
For this APP to work, make sure
Sync Instant Upload is enabled on your phone:
Learn more about how to Configure account sync options, where you can:
Configure general sync settings
Sync information manually
Change an account’s sync settings
After the above introduction on how things work, in order to try and solve this issue, one can:
Check for the Pictures/Screenshots/ folder presence.
e.g., using a file manager.
Check if Instant Upload is Enabled and set to sync with your account.
If all checks out but still no avail, try rebooting the device to see if Media Scanner will properly recognize and add the missing media content to the database.
Not likely, but a recent update or crash may have disrupted the Media Scanner service.