I have enough space , but still unable to install ios 16 (8th gen ipad)

Ypu need to free up free, internal data storage space on your iPad.

You need to start by backing up your iPad to either Apple's iCloud ( you may need to pay for additional, monthly storage space ) or by connecting your iDevice to a an older Mac or Windows PC computer running the latest iTunes or, if a newer Mac with a much newer macOS, like macOS Catalina, or later, use the macOS Finder to do the device backup and/or use some other offsite, “cloud” data storage/backup services, like Google Drive/Photos, BOX, DropBox, Amazon Cloud Drive, Flickr ( for photos/images ), etc.

Then, delete any installed apps that you no longer use or use infrequently enough that they aren't missed (you can always reinstalled any purchased or free apps at some time later, as you need them).

In addition, uninstall any games that appear to be using a sizable chunk of your iPad's internal storage, as well!

Then, thin out/delete any music/videos/movies/TV shows/podcasts/screen recordings/photos-images/eBooks/

eMagazine/iBooks/audio books/Documents/PDFs, etc.

If you use a POP email account on your iPad, delete/thin out any old saved emails that maybe saved to your iPad.

To permanently delete photos/images off of your iDevice go into the Photos app and find the Recently Deleted folder/album and permanently delete any photos/images stored in that folder/album.

Also, you can check to see what other stuff is eating up all your valuable data storage space by going into the Settings App,,General Settings Panel, in the right hand column, tap Storage & iCloud usage panel ( in iOS 11 and later, it’s now called iPad Storage ), in the top Storage Panel, tap the Manage Storage panel, wait for a list of apps to generate that will tell you how much space each app is taking up on your iDevice.

Then, for older iPad models with a Home button, do a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttonsOR

For much newer, larger screen iPad models, without a Home button, try the new hard reset procedure for the new 2018/2020 iPad Pro and iPad Air 4 models.

1. Press and release the volume button closest to the top Power button.

2. Then immediately press and release the Volume button farthest from the top Power button.

3. Then, press and hold the sleep/wake/power button at the top. You will see the Slide to Power off button, but keep on holding down the power button until you see the Apple logo, then let it go.

Once you have performed all the steps, wait for a few seconds and your 2018 iPad Pro will boot up completely to the iPad Pro’s Lock screen.

ALL iOS/iPadOS devices need to maintain, at the very least, a minimum of between 3-6 GBs of free data storage space, AT ALL TIMES, to insure normal/nominal functionalities/operation and general overall performance of any iOS device running iOS/iPadOS.

If not all of this solves your iPad storage issues, your ONLY other option is to do a complete backup, erase and restore of your iPad model.

How to back up your iPhone, iPad, and iPod touch - Apple Support

How to factory reset your iPhone, iPad, or iPod touch - Apple Support

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Good Luck to You!

Your 32GB iPad is always going to be a challenge in managing available internal storage. While you cannot increase the amount of RAM or internal storage in your iPad - as this is fixed during manufacture - you can subscribe to a higher tier of iCloud storage - but this is not a substitute for internal storage.

Upgrade to iCloud+ - Apple Support

Upgrading to iPadOS16 from iPadOS15 temporarily requires a lot of space - considerably more than an in-version point-update that only installs updated system files. A full version update requires download of the entire new Operating System in compressed form. The compressed update is then unpacked and verified, requiring at least as much space again. Once successfully verified, the update can be installed - after which the temporary files can be automatically deleted.

To perform all this as an OTA update from iPad settings, your iPad will temporarily require ~6GB of free space just for the update - this being perilously close to your available free space. Your difficulties illustrate that with additional space needed by the OS to operate, system requirements are likely to be just beyond the available free space.

Be aware that you can perform the update using a Windows PC (with iTunes for Windows installed) or a Mac computer (with iTunes or Finder - as appropriate for the installed version of macOS). Using a computer may resolve your immediate problem - as the update is initially downloaded, unpacked and verified on the computer instead of the iPad. Using a computer to perform the update relieves your iPad of having to provide all the temporary storage space.

This support page outline both of the available methods by which the update can be performed:

Update your iPhone, iPad or iPod touch – Apple Support

If your iPad internal storage has insufficient free space to perform the update, you need to manage the storage that you have - and delete unused Apps or unneeded data. Temporarily moving some data to cloud or external storage may be adequate to provide sufficient temporary storage to perform the System Software update.

These support pages should prove to be helpful:

About storage on your device and in iCloud – Apple Support

What's the difference between device storage and iCloud storage? – Apple Support

Manage your iCloud storage – Apple Support

How to check the storage on your iPhone, iPad and iPod touch – Apple Support

Clear Other storage on your iPhone or iPad - Apple Support

“Offloading” Apps can be a helpful method of creating temporary space for a software update.

https://9to5mac.com/2020/01/21/how-to-offload-apps-in-ios-to-save-space-without-deleting-their-data/

Additional information about creating sufficient space for installation of a software update can be found here:

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

External storage options can often help with managing limited internal storage. Depending upon your iPad model, the iPad will either have a Lightning or USB-C port - and may therefore require either an Adapter or USB hub to connect the USB Storage device. If your iPad has a Lightning port, you’ll need an Apple Lightning to USB3 Camera Adapter:

• Lightning to USB 3 Camera Adapter

https://store.apple.com/uk/xc/product/MK0W2ZM/A

In summary, if you have access to a Windows PC or Mac computer, this may be the easiest method by which to perform a System Software update if available internal storage is insufficient. Otherwise, you must create adequate free-space, at least temporarily.

Uh, no.

Your iPad does not have enough free, internal data storage space.

As a matter of fact, you have, basically, completely filled your iPad full of data.

A 32 GBs storage iPad starts out with approx 30 GBs.,after initial internal flash drive formatting.

Minus approx. 6.5 GBs for iOS/iPadOS leaves between 23-24 GBs.

Minus 3-6GBs, for iOS/iPadOS system operational reserve, that MUST BE MAINTAINED AT ALL TIMES, to ensure/insure normal, expected operation of iOS/iPad OS, leaves approx. between 18-20 GBs of actual, usable data storage space.

Even with 20 GBs of actual, usable internal data storage space in an Apple iOS/iPadOS device,

a 32 GBs data storage devices are, now, more quickly, becoming the “new” low storage 16 GBs internal data storage space devices, today, a 32 GBs Apple iOS/iPadOS device has 3-4 times the internal data storage space of older base model, low internal data storage,16 GBs. internal data storage Apple iOS/iPadOS devices.

In reality and in use, in 2022, a 32 GBs internal data storage device is kind of a joke and of limited usefulness, when up to 2TB of internal data storage ( approx. 1.8 TBs or usable internal data storage ) portable tablet devices exist today.

Apple put an end to 32 GBs devices, in September 2021, with the base model iPad now offering 64 GBs of internal data storage ( approx. 50 GBs of actual, usable internal data storage ), which, for a few more years, anyways, has enough storage to make an iPad useful for longer period of time before data storage fills up.

Purchasing a low storage Apple device, to save on the cost of the device, is a false economy.

Not only do you need to free up 5-7 GBs of internal data storage space to regain enough system critical operational storage space, yoy will need to free up another 6-8 GBs to be able to install either iPadOS 15.7.1 or iPadOS 16.1.1.

So, you need to free up a total of 10-12 GBs on that iPad.

If you're still having issues: your initial post seems to show a large amount of space taken up by 'Other'. Please see this discussion about how to recover that space: System data - Apple Community