System data on MacBook Air increased to 96GB after Golden Gate update

"System Data" comprises your data, but they are files that Spotlight cannot assign to a specific category like Documents or Applications. Examples include Outlook attachments, Cloud storage caches, and Time Machine snapshots. 

Follow the steps in this User Tip:

How to free up ‘System Data’ and other st… - Apple Community

System Data can be kept to a reasonable amount, for example on my personal Mac it is around 21 GB right now (it's varied from 9 GB to 40 GB over the past weeks).

However, on my work Mac where I use MS Outlook heavily, it is well over 100 GB (in large part due to inline email attachments stored in the Library, as described in the above-linked User Tip).

Here are some steps to take to safely free up space:

Free up storage space on Mac - Apple Support

Optimize storage space on your Mac - Apple Support

How to free up ‘System Data’ and other st… - Apple Community

One important thing to know about "System Data" is that it is based on Spotlight indexing, and after a macOS update your Mac will rebuild the Spotlight index. That process can take some time.

About Spotlight indexing and search results on Apple devices - Apple Support

Let it complete, and if that doesn't help you can initially force a re-index manually:

Rebuild the Spotlight index on your Mac - Apple Support

From there, proceed to the steps here:

How to free up ‘System Data’ and other st… - Apple Community

A change in System Data from 25 GB to 96 GB after upgrading your MacBook Air to macOS 27.0 (Golden Gate) does not, by itself, indicate a problem.

Apple describes System Data as a general category containing files that do not fall into other storage categories, including system files, caches, log files, virtual-memory files, temporary files, and other system resources. 

Its size can vary depending on the current state of the Mac, and macOS manages its contents. (Apple Support)

The 96-GB figure therefore does not by itself establish whether the increase is temporary, permanent, or specifically caused by the macOS upgrade. 

I would not manually delete files from System Data.

After the upgrade has completed, restart the Mac and check System Settings >> General >> Storage again. 

Pay particular attention to Available storage. 

If you have plenty of available space, the System Data figure alone may not require any action. 

If available storage is significantly reduced or continues to decrease, the storage usage can then be investigated further.

Apple's guidance is available here: Free up storage space on your Mac and Change Storage settings on Mac.

Use another application to see where space is being used DaisyDisk 

View APFS snapshots in Disk Utility on Mac

Stop Chrome Browser From Downloading a Hidden 4GB AI File

From a fellow contributor How to Use Finder to Clear “System Data" … - Apple Community

Suggest getting an External SSD Drive and start moving your Pictures, Videos, Music and any other large files you have control over, OFF the Internal drive and Onto the External

smartblondegirl wrote:

System data went from 25GB to 96GB after updating to Golden Gate on Macbook Air--is this normal?

After a major update the answer is yes, that’s normal. It should drop as time progresses.