Device storageand select the files and folders you want to move by ticking the boxes next to them But for those that notice the internal storage isn't full on your Galaxy J5 and you still see the error message, then it's suggested to delete your cache. Turn off the Galaxy J5.
This might be due the cache file located in your phone. Just clear all the apps cache file. To do so follow the below procedure.
1. Go to settings and search for Apps and Notifications.
2. Just click on the Apps and Notification icon, after clicking you will see all the apps which is there in your mobile.
3. So click on one of the app, after clicking you will see storage and cache option, just click on that option, after clicking you will see two options clear storage and clear cache. Just click on clear cache option.
4. Follow the above steps for all the apps