Issue Description
My Mac originally had macOS 26.2, and I updated it to macOS 26.6. After using Safari normally for 2–3 days, Safari suddenly crashed.
After the crash, when I open Safari again, it sometimes launches as a new/empty Safari instance instead of opening my existing Safari profile. My bookmarks, history, tabs, and other Safari profile data are not available in this new instance.
While investigating the issue, I found a folder under my Mac's Library whose name appears to be my Mac's serial number/hardware identifier. This folder contains Safari-related files.
I believe this serial-number-named folder may be related to the problem. My concern is that this folder may be causing Safari to create or open another Safari instance/profile after Safari crashes. If this folder is incorrectly created or recreated, it may explain why a new Safari instance appears and why my original Safari profile is not loaded.
I have already contacted Apple Support and tried the following:
- Created and tested with a new macOS user
- Tested in Safe Mode
- Cleared Safari cache and cookies and checked Safari Library data
- Restarted the Mac multiple times
- Reinstalled macOS
- Completely erased the internal drive
- Performed a fresh macOS installation
- Updated macOS to the latest available version
The issue still occurs even after completely erasing the drive and performing a clean macOS installation.
I am also currently seeing two different Safari icons/appearances on my Mac: one appears to be the newer macOS 27 Safari icon, while another appears to be the older macOS 26 Safari icon.
Request to Apple
Please investigate the serial-number-named folder specifically and determine:
- Why this folder is created.
- Which macOS or Safari process creates it.
- What its purpose is.
- Whether it is related to Safari profiles, containers, application registration, or Safari instances.
- Whether this folder can cause Safari to launch as a new/empty instance after a crash.
- Why the folder or related Safari state can appear again even after a completely clean macOS installation.
- Why two different Safari icons/appearances are currently present.
I believe identifying the source and purpose of this serial-number-named folder may help identify the root cause of the Safari issue.
I do not want to delete or modify this folder without Apple's confirmation because it may be a system-managed folder.
Please investigate this as a possible macOS/Safari system-level issue and escalate it to the Safari/macOS engineering team if necessary.
I can provide the exact folder path, screenshots, Safari crash reports, system logs, and Terminal output showing the Safari application locations and related folders.