User level: Level 1 (4 points)Has anyone had serious problems after installing upgrade macOS Sequoia 15.8.1? How can it be fixed?
Posted on Oct 23, 2026 8:56 AM
User level: Level 9 (78,350 points)Oct 23, 2026 10:30 AM in response to Kathy10Mac
If you are having issues after updating to macOS 15.8.1, then we need to know the specific issues you are experiencing. It would also help to know whether you were already running Sequoia and just installed a minor update patch to 15.8.1 or whether you were using another older OS and upgraded to Sequoia.
It would also help to know the exact model of the computer. You can get this information by clicking the Apple menu and selecting "About This Mac".
Very general troubleshooting steps would be to disconnect all external devices in case one of them is causing a problem. Another troubleshooting step is to boot into Safe Mode to see if the problems still occur while using the computer in Safe Mode. If the problem does not exist while booted into Safe Mode, that will provide a valuable clue as the problem is most likely due to third party software.
You can also provide us more details on your specific issues. Run the third party app EtreCheck and post the complete report here so we can examine it for possible clues. It is best to wait until after you experience the problem before running EtreCheck so it can possibly capture relevant performance metrics.
How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community
You should also read the following article for tips when asking for help online so that we start off with some relevant details:
Writing an effective Apple Support Communities Question - Apple Community
User level: Level 10 (99,154 points)Oct 23, 2026 9:38 AM in response to Kathy10Mac
We have no problems running macOS 15.8.1 Sequoia on a couple of our Mac's.
To prevent from having to play 20 questions about your specific problems.
Download and run the free version of EtreCheckPro, from > https://etrecheck.com/en/index.html
Then post back here with your Report, as per > How to use the Add Text Feature When Post… - Apple Community
User level: Level 9 (78,350 points)Oct 26, 2026 6:54 AM in response to Kathy10Mac
Uninstall both Bitdefender and Norton by following their developer's instructions. Just deleting the app is not enough since they installed tendrils into the lower levels of macOS. Anti-virus software, cleaning & optimizer apps, and third party security software are not needed on a Mac and will usually cause more problems than they solve because they all interfere with the normal operation of macOS.
After uninstalling those apps, you may want to run another EtreCheck report to make sure there are no more signs of either app.
Also, we posted links with instructions on how to attach an EtreCheck report here. In the future, please attach the reports using those instructions.
User level: Level 10 (99,154 points)Oct 24, 2026 1:58 PM in response to Kathy10Mac
That is only the first part of the EtreCheckPro report.
To post the entire EtreCheckPro report, use the following instructions.
How to use the Add Text Feature When Post… - Apple Community
User level: Level 1 (4 points)Oct 24, 2026 5:40 PM in response to Kathy10Mac
User level: Level 9 (78,350 points)Oct 23, 2026 6:21 PM in response to Kathy10Mac
Kathy10Mac wrote:
The previous version of MacOS Sequoia was installed before the 15.8.1 update installed on 10/21/26. Now I can not open any Youtube videos, I can not post on X, Instagram or anywhere. My laptop gets locked up.
Thanks for those details.
Please run the third party app EtreCheck and post the complete report so we can examine it for possible clues.
How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community
User level: Level 1 (8 points)Oct 25, 2026 7:39 AM in response to Caesar79AD
I did the Sequoia 15.8.1 upgrade on my MacBook Air last night and have the exact same issue this morning. I cannot even play BBC iplayer videos.
I have just downloaded the Chrome Browser and I can play YouTube videos and the BBC Iplayer is ok.It looks like the problem is with the Safari browser. I have tried clearing the history cache but it didn't fix it in Safari.
User level: Level 1 (4 points)Oct 24, 2026 1:54 PM in response to HWTech
EtreCheckPro version: 6.8.17 (68099)
Report generated: 2026-10-23 10:25:17
Download EtreCheckPro from https://etrecheck.com
Runtime: 6:56EtreCheckPro version: 6.8.17 (68099)
Report generated: 2026-10-23 10:25:17
Download EtreCheckPro from https://etrecheck.com
Runtime: 6:56
Performance: Below Average
Problem: Other problem
Description:
I can not watch any YouTube videos
X gets stuck
Other apps get hung up
Major Issues: None
Minor Issues:
These issues do not need immediate attention but they may indicate future problems or opportunities for improvement.
No Time Machine backup - Time Machine backup not found.
Apps crashing - There have been numerous app crashes.
Apps with heavy CPU usage - There have been numerous cases of apps with heavy CPU usage.
Runaway user process - A user process is using a large percentage of your CPU.
Low performance - EtreCheck report took an unusually long time to run.
Kernel extensions present - This computer has kernel extensions that may not work in the future.
Hardware Information:
MacBookAir9,1
Status: Supported
MacBook Air Model: MacBookAir9,1
1.1 GHz Dual-Core Intel Core i3 (i3-1000NG4) CPU: 2-core
8 GB RAM - Not upgradeable
BANK 0/ChannelA-DIMM0 - 4 GB LPDDR4X 3733
BANK 2/ChannelB-DIMM0 - 4 GB LPDDR4X 3733
Battery: Health = Normal - Cycle count = 174
Video Information:
Intel Iris Plus Graphics - VRAM: 1536 MB
Color LCD (built-in) 2560 x 1600
Drives:
disk0 - APPLE SSD AP0256N 251.00 GB (Solid State - TRIM: Yes)
Internal PCI-Express 8.0 GT/s x4 NVM Express
S.M.A.R.T. Details: 21% used, 295.07 TB written, 100% health, 121 unsafe shutdowns
disk0s1 - EFI [EFI] 315 MB
disk0s2 [APFS Container] 250.69 GB
disk1 [APFS Virtual drive] 250.69 GB (Shared by 6 volumes)
disk1s1 (APFS) [APFS Container] (11.26 GB used)
disk1s1s1 - Macintosh HD (APFS) [APFS Snapshot] (11.26 GB used)
disk1s2 - Macintosh HD - Data (APFS) [APFS Virtual drive] (137.12 GB used)
disk1s3 - Preboot (APFS) [APFS Preboot] (2.78 GB used)
disk1s4 - Recovery (APFS) [Recovery] (1.34 GB used)
disk1s5 - VM (APFS) [APFS VM] (1.07 GB used)
disk1s6 - Update (APFS) (2 MB used)
Mounted Volumes:
disk1s1s1 - Macintosh HD [APFS Snapshot]
Filesystem: APFS
Mount point: /
Read-only: Yes
Used: 11.26 GB
Shared values
Size: 250.69 GB
Free: 96.97 GB
Available: 111.86 GB
disk1s2 - Macintosh HD - Data [APFS Virtual drive]
Filesystem: APFS
Mount point: /System/Volumes/Data
Encrypted
FileVault Enabled
Used: 137.12 GB
Shared values
Size: 250.69 GB
Free: 96.97 GB
Available: 111.86 GB
disk1s3 - Preboot [APFS Preboot]
Filesystem: APFS
Mount point: /System/Volumes/Preboot
Used: 2.78 GB
Shared values
Size: 250.69 GB
Free: 96.97 GB
disk1s5 - VM [APFS VM]
Filesystem: APFS
Mount point: /System/Volumes/VM
Used: 1.07 GB
Shared values
Size: 250.69 GB
Free: 96.97 GB
disk1s6 - Update
Filesystem: APFS
Mount point: /System/Volumes/Update
Used: 2 MB
Shared values
Size: 250.69 GB
Free: 96.97 GB
USB:
USB 3.1 bus
<Empty>
USB 3.1 bus
<Empty>
T2Bus
Apple Inc. - Touch Bar Backlight
Apple Inc. - Apple Internal Keyboard / Trackpad
Apple - Headset
Apple Inc. - Ambient Light Sensor
Apple Inc. - FaceTime HD Camera (Built-in)
Apple Inc. - Apple T2 Controller
Network:
Interface en0: Wi-Fi
802.11 a/b/g/n/ac
Interface bridge0: Thunderbolt Bridge
iCloud information is limited without Full Disk Access
System Software:
macOS Sequoia 15.8.1 (24H32)
Installed 2026-10-21
Time since boot: About 17 hours
User level: Level 1 (4 points)Oct 24, 2026 2:10 PM in response to Kathy10Mac
Performance:
System Load: 3.25 (1 min ago) 5.59 (5 min ago) 4.73 (15 min ago)
Nominal I/O usage: 0.10 MB/s
File system: 46.92 seconds
Write speed: 740 MB/s
Read speed: 1129 MB/s
CPU Usage Snapshot:
Type Overall
System: 11 %
User: 21 %
Idle: 68 %
Top Processes Snapshot by CPU:
Process (count) CPU (Source - Location)
com.apple.WebKit.GPU 99.68 % (Apple)
WindowServer 11.50 % (Apple)
EtreCheckPro 6.52 % (Etresoft, Inc.)
biomesyncd 6.20 % (Apple)
kernel_task 4.03 % (Apple)
Top Processes Snapshot by Memory:
Process (count) RAM usage (Source - Location)
EtreCheckPro 832 MB (Etresoft, Inc.)
com.apple.WebKit.WebContent (6) 738 MB (Apple)
kernel_task 163 MB (Apple)
AppleSpell 147 MB (Apple)
Safari 133 MB (Apple)
Top Processes Snapshot by Network Use:
Process Input / Output (Source - Location)
mDNSResponder 3 MB / 3 MB (Apple)
com.norton.mes.networkextension 1 MB / 269 KB (NortonLifeLock, Inc.)
com.apple.WebKit.Networking 1 MB / 249 KB (Apple)
apsd 68 KB / 419 KB (Apple)
com.norton.daemon 91 KB / 80 KB (NortonLifeLock, Inc.)
Top Processes Snapshot by Energy Use:
Process (count) Energy (0-100) (Source - Location)
com.apple.WebKit.GPU 40 (Apple)
WindowServer 3 (Apple)
cloudd (2) 1 (Apple)
launchd 0 (Apple)
Safari 0 (Apple)
Virtual Memory Information:
Physical RAM: 8 GB
User level: Level 1 (4 points)Oct 26, 2026 8:32 AM in response to Caesar79AD
Thanks. I installed Chrome and I'm able to post and use Youtube, etc. I don't want to use Chrome, but it works!
User level: Level 1 (4 points)Oct 23, 2026 3:00 PM in response to HWTech
The previous version of MacOS Sequoia was installed before the 15.8.1 update installed on 10/21/26. Now I can not open any Youtube videos, I can not post on X, Instagram or anywhere. My laptop gets locked up.
User level: Level 1 (4 points)Oct 24, 2026 2:05 PM in response to Kathy10Mac
User level: Level 1 (8 points)Oct 26, 2026 9:45 AM in response to Kathy10Mac
I have just been setting up favourites in Chrome also :-), it is good to have a backup browser for issues like this.
I noticed on your report it updates the Safari to version 27 like I have on mine, so I suspect that.
I don't have any Bitdefender or Norton anti virus on my Mac and I have the same issues as you so I am not sure taking them off will fix it.
User level: Level 1 (8 points)Oct 25, 2026 6:55 AM in response to Kathy10Mac
I did the Sequoia 15.8.1 upgrade on my MacBook Air last night and have the exact same issue this morning. I cannot even play BBC iplayer videos.
Originally posted at discussions.apple.com/thread/256381595