Internal memory nearly full

The internal memory on my Galaxy Tab S3 shows 96% full using the app ES file explorer/manager. I have used several apps to transfer data to a installed SD memory card so that most folders on the internal memory reports little data with ES. Moreover, uninstalling an app or two shows no difference in the 96% full report.

What can I do? Reformat the tablet is the only thing that comes to mind; or buy a later version of the tablet (much work to connect to maybe 10 IMAP email addresses, or entering passwords to many other apps).

What should I do to free up main memory on this tablet?


Spacecorp test pilot
The first thing to do is to identify what is actually using the space. Without knowing that any changes you make may be missing the problem completely.
Can you post some screenshots of what the system storage menu says? It's important to know that a user-installed file manager won't be able to show you anything about the private data of apps; my advice would be to see whether the "app manager", as I believe Samsung call the "apps" section of the system settings, can show you your apps ordered by size (some can, some can't. If you can't see the option look for a 3-dot menu icon and see whether it's there). If you can identify which are the big space users you'll know where to start: simply clearing caches of browsers or social media apps can sometimes free up GB of space, and if you are going to uninstall apps (a more permanent solution) then knowing which ones are worth uninstalling is important.

Those of us who don't have this device might also like to know how much storage it has in the first place. If it's an 8GB device you'll probably always struggle with storage (at least half of that will be used by the OS, so you'll only have a few GB in total even after a reset).

As an aside, ES have had a lot of privacy and data protection issues. They wouldn't be my first, or even thirty-first, choice of file manager.