iPhone system data filling up device after iOS 26 update

I know many will probably disagree. But such a big update from iOS 18 to iOS 26 should be done as a "clean" update. I personally don't see the point of iCloud Backup anymore. All your photos, files, contacts, etc. are continuously backed up, and it's automatically downloaded when you sign in with your Apple Account. Apps can just be downloaded again in the App Store.

The only advantage I can see is that the wallpaper and apps are in the same place on the screen after you restore from an iCloud Backup. But often you have to sign in to all the apps again anyway.

Here's how I do it. I make sure iCloud is up to date, so that all photos, files, etc. are synchronized. After that, I sign out of my Apple Account. Then I choose Erase All Content and Settings. When the phone is restored to factory settings, I connect it to my Mac (can also be done from PC, iTunes), and then I do a restore, where everything is wiped again and the latest full update is downloaded and installed.

Once that's done, I set up the phone as new without a backup. Then I sign in with my Apple Account, so that photos, contacts, files, calendar, etc. are synchronized back to the phone. Then I download the apps I use again from the App Store, and set them up one by one.

That way you get a clean start. By using the backup, you drag everything, including your problems, onto a new software - or a new iPhone. It can be time-consuming. But in return, you have an iPhone that just works, and you get rid of all the system data that has accumulated.

"iPhone system data filling up device after iOS 26 update: [...]Tech support contacted me and was poking at the amount of apps that I have offloaded (it was hundreds of app). They recommended I either delete the offloaded apps or download the app in full and see if that fixes anything. I deleted hundreds of offloaded apps. Since then - so far so good![...]"

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Clearing Caches:

What you did shows this is all caches. So, rather than trashing all of those apps, you should have performed my User Tip : How to Clear "System Data" in your iPhone's Storage: - User Tip

Having Deleted these...

Now, you need to redownload them --with nothing to go by, you'd have to restore from a backup of these apps, or a from screenshots you have that show which apps were deleted, and where they were stored on each Home Screen.

I agree 100% on a clean install, if you find it necessary. I just did that on my Mac after upgrading first from the Sequoia to Tahoe 26.2. Erasing the disk and doing a clean install of Tahoe 26.2 left me with a lot more free space and Tahoe 26.2 looks and works as designed. I'm guessing that's because it didn't have to try and re-instate any of my old Sequoia settings. There's a lot of new features and changes in Tahoe 26.2. This has been a valuable lesson. Next major MacOs update, I will probably wipe the drive and do another fresh install.

I disagree on your iCloud Backup remark. I have multiple Apple devices and I have the Apple One plan with all of their services and 2TB of iCloud space, which I share with my daughter (it automatically keeps our data separate). Because of the Keychain, Passwords, Contacts, Messages, Photos, iCloud Drive, etc., I can clean any device I have and not worry about my data. It's all on iCloud. When I work in any app, whether it be Pages, Numbers, Keynote, or 3rd party, I have them set to save my files to iCloud, not locally.

Until I had multiple Apple devices, I didn't appreciate the scope of Apple's ecosystem. How could I? I wasn't aware of how good it was at centralizing and protecting my data, provided I use iCloud. For me, iCloud is superior to TimeMachine on Mac, though I use both. You can never have too much data backup or data security.

Johne154 wrote:

...

I disagree on your iCloud Backup remark. I have multiple Apple devices and I have the Apple One plan with all of their services and 2TB of iCloud space, which I share with my daughter (it automatically keeps our data separate). Because of the Keychain, Passwords, Contacts, Messages, Photos, iCloud Drive, etc., I can clean any device I have and not worry about my data. It's all on iCloud. When I work in any app, whether it be Pages, Numbers, Keynote, or 3rd party, I have them set to save my files to iCloud, not locally.

...

I understand, but we see many owners in the forum who positively, idealogically, object to paying Apple a cent for storage, so generally we advise making a backup of some sort, if only for those who thought they had everything sync'd but didn't.

Here's my counter to all that idealism:

It only takes losing your precious data, like your or your children's wedding photos, or new baby pictures, or songs or book you wrote, to appreciate the value of losing everything.

I dare say that people spend more on a single streaming TV/movie service than it would cost to use iCloud.

For just additional iCloud storage alone, no other Apple service, Apple's additional iCloud rates are well worth it.

I'm long retired from IT, where data security, data backup, and disaster plans were always top of the list.

If your house got washed away in a flood or burned down in a fire, what would the impact of your data loss be on top of that disaster?

Also, Technology changes over time. A backup device that works today, may be obsolete tomorrow!

Don't learn from your own mistakes, when you can learn from the mistakes others have already made before you.

Johne154 wrote:

Here's my counter to all that idealism:

It only takes losing your precious data, like your or your children's wedding photos, or new baby pictures, or songs or book you wrote, to appreciate the value of losing everything.

I dare say that people spend more on a single streaming TV/movie service than it would cost to use iCloud.

For just additional iCloud storage alone, no other Apple service, Apple's additional iCloud rates are well worth it.

I'm long retired from IT, where data security, data backup, and disaster plans were always top of the list.

If your house got washed away in a flood or burned down in a fire, what would the impact of your data loss be on top of that disaster?

Also, Technology changes over time. A backup device that works today, may be obsolete tomorrow!

Don't learn from your own mistakes, when you can learn from the mistakes others have already made before you.

Absolutely, you don't need to sell that to the regulars - Stick around Johne154!

It took me a number of years to work out that paying for a modest 200GB iCloud worked out far less expensive than getting a 256GB device every 2-3 years. I run 64GB devices with no problems, Who on earth needs a 2TB phone?

NO.

Same Issue even after Upgrading to iOS 26.2.

I have Restored Twice Since Installing iOS 26.2 to no Avail...

Pretty ****** Right Now...