Internal drive turns read only

I am using ubuntu 16.04 and have an internal 8tb harddrive which I want it to be mounted to all users on my machine both admins and not.

I've created a folder called 8tb in /media/8tb

Then I added the below to /etc/fstab

/dev/sda /media/8tb ext4 user,defaults 0 1

The harddrive keeps switching to readonly after using it for some time then when I unmount it and remount it it shows the below message asking for an admin account to mount it, not sure what the problem is?

Here is how it looks in the disks:

If I mount it with an admin account I get this error message:

Although in the sudoers file I have this added allowing the non-admin account I have to mount without sudo

my_non_admin_user    ALL=(ALL) NOPASSWD: /sbin/mount.cifs, /bin/mount, /bin/umount

I tried changing the fstab file to be like this:

/dev/sda /media/8tb ext4 user,defaults 0 2

or

UUID=629f755c-a29e-43bd-ad02-8deec4abdddb /media/8tb ext4 user,defaults 0 2

But still the same thing happens and it turns read only and

and this is the result of ll /dev/sda:

brw-rw---- 1 root disk 8, 0 jun 10 22:24 /dev/sda

I've run dmesgjournalctl and S.M.A.R.T and placed the results in this link

I wonder what might be the reason the drive suddenly turns read only? And how to avoid this?