System Data is taking up 54.91 GB on my iPhone 13 Pro with iOS 26

TLDR: Use a computer to do the update if you are low on space; ios 26.1 does not seem to have the same space-hogging bug that 26.0.x did.

I had a similar issue- system data took up massive amounts of space on my iphone 14 pro with 128gb of storage forcing ios to offload apps and "optional" data (like offline language, maps, etc.) frequently, and leaving me unable to store offline music or videos and forcing most of my apps to be in an offloaded state. I've been using iphones since the beginning and I have never ever run out of space for apps and music. I was unable to install the ios 26.0.1 update without deleting a ton of stuff off my phone, so I was desperate to try the ios 26.1 update hoping it would fix the problem... .of course with 118gb used out of 128 it refused to install. Luckily I had my mac handy and I was able to do the ios update using the mac and it worked without any problems. And so today, without deleting or offloading anything vs. yesterday I now have 40gb free. This leads me to agree that there was a bug in iOS 26.0 and .0.1 that is now resolved in 26.1. For anyone blocked from upgrading to 26.1 due to storage being too full of ios data, I recommend using a computer to do a backup and update.

The abnormal growth and speed of growth can be traced to both third party apps and Apple apps. Third party apps frequently use System Data for their caches.

Common apps that do this are streaming apps like YouTube, Spotify, Amazon Video, and Netflix etc. Social media apps like Facebook, Instagram, WhatsApp, TikTok, Discord. Sometimes when you just delete the app, it moves its cached data to System Data.

Apple maybe partially to blame too. Safari and Messages (iMessage) cache data too. When the iOS is upgraded or updated background syncing, indexing etc. can cache large amounts of data.

Whatever apps are doing this, they can’t do it without consuming battery capacity. What apps are using the most battery capacity on a day to day basis?

Restoring is the usual method of reducing delinquent system data. It can be caused by gaming apps, social media apps, or beta testing. It would not be reduced by an update normally unless using a mac ti update it.

I’ve never enjoyed that kind of reduction by OTA update, glad it worked for you.

Fir the rest of us, if the space is needed then backup, erase, restore,

Yes, but the only way to shrink System Data back to normal size is to erase the device, in most cases.

If the System Data growth is from wallpaper and lock screen manipulation, only a full reset works so far.

System time and ProRes tricks only ever clear 1-2GB for me.

I’m averaging one full reset a week 🤷🏻‍♂️

Rcinkle wrote:

If the System Data growth is from wallpaper and lock screen manipulation, only a full reset works so far.

System time and ProRes tricks only ever clear 1-2GB for me.

I’m averaging one full reset a week 🤷🏻‍♂️

Gaming, badly behaved social media and beta testing are surely a bigger creator of rogue system data than wallpaper?

Eventually upgraded to 26.1 which took ages. After the phone being on for around 10 minutes the system data usage dropped massively to around 16.5GB. Much better than the 70GB that it was before. Nothing in the 26.1 release notes to say it was a bug.

First turn off AI

If that fails to reduce storage in a few days, use iCloud or other cloud fully on all your data. Sync fully.

You can then restore to factory and set up without a backup

Build from scratch and only install really essential apps as you need them.

Avoid games, AI, and security apps.

-thoraxx- wrote:

It seems to me that IOS 26.2 does not fix this...

Nothing to fix, turn off AI will make a big difference.

And/or

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

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

 if it comes back later after using Games, that is the cause.

Just turning of mail and deleting the accounts and app would not necessarily decrease any caches in system data. The test would be to delete the app(s), backup the device, erase the device and then restore from backup. Mail would not be installed and System Data size would reflect any changes from caches being deleted.

Mail app, however, has its own unique category and generally doesn’t cache any data in System Data.

I never used my MacBook to update iOS. I did it from the Settings app on my iPhone.

Once the update completed, my system data usage dropped sharply. Restarts didn't help my issue before, nor did the system time change. Restoring was going to be my absolute last resort if the update didn't help things (which it surprisingly did, implying it was an iOS bug all along.)

NetSecNW wrote:

Eventually upgraded to 26.1 which took ages. After the phone being on for around 10 minutes the system data usage dropped massively to around 16.5GB. Much better than the 70GB that it was before. Nothing in the 26.1 release notes to say it was a bug.

How did you update, OTA or on a computer?

"[...]I think it’s hilarious that apple doesn’t give us a way to clear or at least debug and monitor this part of the filesystem. A complete restore from backup always takes a few hours in my case…"

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Clearing System Data:

Clearing System Data:

That's the way it is. So, turn off all network connections, and perform this in Safe Mode --that way, less network data traffic will occur, and login items will not open at login. For reference, see my user tip: How to Clear "System Data" in your iPhone's Storage - Apple Community

Just for the Record:

This has been Apple's method since the late 2010s. On a phone call with Apple Support in late 2019, Apple ran me through the fix, and then I authored the User Tip, once had earned the points to do so, making a few modifications over the years, as new releases came about. See here: How to Clear "Other" in your iPhone's Storage - Apple Community