On Android, if you receive the error Scan failed on [/] with error code 13 when using SyncBack Touch then please change the directory that is used on Touch for the profile, e.g. change it to \sdcard\
Error 13 is an access denied error. Changes since Android 7.0 (Nougat) mean applications no longer have access to the root directory (\). Because of this it is recommend you set your Touch directory to \sdcard\
Since Android 11 Google has implemented stricter security policies related to which folders/files applications can access, causing breaking changes as a result. The same problem happened in the past with every major version update, Google tightening security every time.
We advise users to only backup Android folders that contain personal content, such as media, photos, documents and to avoid selecting all the folders on the device because most of them are application data and settings which are kind of useless, since they can't be restored, plus they are inaccessible and give errors during backup.
If you are having problem with backing up some folders, try excluding from your backup any folders that give you an error code 13 (such as /sdcard/Android/data). That error code is essentially an access denied error from Android itself meaning the application is not allowed to access it due to permissions/access rights. You may have given the application permission to access all files but still some locations are off limits.
To exclude these folders, edit your profile and in the Simple tab press the "Choose sub-directories and files" button to open the folder/file selection form. There you can unselect any folders causing you problem.
If you need to access the device's external SD card then you may use the %SBT_EXTSDCARD% variable in the profile's source/destination directory instead.