iPhone system data filling up device after iOS 26 update

I had this problem too with the upgrade on my iPhone 12 Pro Max.

One of the thing that seems have solved it is to disable the automatic download of new system updates (General-Software Update) because iOS was reserving space for them (almost 12 GB).

I have the exact same problem with my iPhone 15 Pro 256GB version. I had more than 130GB of free space but after updating to iOS26 the system data started filling up any empty space.

I cant even receive emails now!

Apple please fix this as it must be some kind of bug.

Same problem for me. It’s killing my iPhone 15 Pro. 64GB of system data and even if I delete apps it keeps filling the space. Wiped and restored, plenty of space, then 2 weeks later it’s back up to full. Apple please fix this ASAP. My phone is becoming useless. And, please provide users more control and visibility over system data so we can see what is going on.

Yep. Back to full. Disappointed. Like you I will have to do this every two weeks. Productivity killer so I hope it get fixed soon. It’s brutal. iOS 26.1 Beta 4 is available but I haven’t tried it. Need to wipe my phone again to make space.

"iPhone system data filling up device after iOS 26 update: [...]I ended up backing up the device, wiping it, and restoring it from backup and I noticed that i had about 60GB of space free. [...]Can anyone give me some advice here?"

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To the OP and All those Affected:

A. Properly Clearing System Data After an Update:

The erasure between the backup and then restore may be the issue here, as it is not a required step In this process. Here is my User Tip on how to clear of the System Data: How to Clear "System Data" in your iPhone's Storage: - User Tip

B. Report this Bug to Apple:

Do your Part: These are user-to-user forums. Apple rarely reads these forums on their own time as it is. So, provide Apple with feedback on this.  Apple wont get back to you directly, but the more they hear of this, the more they will know what is going on, and what needs to be fixed.

To Provide Feedback:

1. Go Here: Feedback - iPhone - Apple
2. Select: "Bug Report" for the "Feedback Type"
3. Comment: when this all began, and how you have troubleshot this thus far. Include the URL of this thread.
4. Proceed form there as necessary

[HELP HELP HELP]

I am Having the Same Issue.

iPhone 15 Pro Max with 90GB Free on iOS 18.7, with no issues at all.

But since iOS 26, iPhone keeps Running out of Memory and the System Data keeps Ballooning,

After Restoring Multiple Times, and Multiple Calls to Apple.

if anyone gets a Resolution, Please Post it.

“[…]But since iOS 26, iPhone keeps Running: out of Memory and the System Data keeps Ballooning, After Restoring Multiple Times, and Multiple Calls to Apple. if anyone gets a Resolution, Please Post it.”

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Clearing System Data in a Loop After Update:

A. Use my User Tip:: How to Clear "System Data" in your iPhone's Storage: - User Tip

B. Reset to Factory Settings:

If still getting this issue, you may need you backup your iPhone to a computer, and then reset it to Factory Settings. Look into taking a few screenshots, and then email them to yourself, as a way to remember what when where, and how things were configured. Enabling Items in iCloud (ie Photos and Messages), you can back them up, if you have free storage to do so.

"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.