System.log error after latest Security Update 2020-005 for Mojave from Sep 24th 2020

I ran Disk Utility from Recovery Mode to ensure that my Time Machine drive (external USB) was not corrupted, and then reinstalled from a Time Machine backup that I made a few hours before applying the update.

I chose the option to erase my HD and install both the Mac OS X system files and my user files.

I did not lose any data (Keychain PWs, Safari PWs, Mail accounts, Network setup, Documents, Apps, etc., etc.)

Recovery mode also worked for me. I didn't backup before installing the update, and I have "Backup Automatically" turned off, but apparently the install created a local Time Machine snapshot anyway.

So restarted with Cmd+R, restored from that, all is well again. No more syslog spam or duplicate class implementations, and Activity Monitor now shows about 3GB memory used on startup instead of over 8GB (that is probably what is causing the slowdowns reported in many other threads, I have 16GB total so didn't have that problem).

Hopefully this works for others.

Those suggestions were to be done after re-installing Mojave. I was replying to sarahara.

Your options if 2020-005 is still installed are;

1. Restore from the Time Machine automatic local snapshot created by the update install. This has to be done within 24 hours or the snapshot gets deleted.

2. Restore from a Time Machine backup made before the install.

3. Re-install MacOS Mojave (a re-install will keep all your files and apps), then do what I suggested.

4. Upgrade to Catalina.

See sections 5 and 6 of this post if you need more detail on how to restore or re-install https://mrmacintosh.com/mojave-2020-005-security-update-causing-major-problems-updated/

I had a similar experience.

I installed the update and immediately my 21.5" (late 2013) iMac became unusable (beach balling on every mouse click; my Time Machine backup disk showed NO backups had been made; EtreCheck showed MAJOR issues; etc., etc.)

I spent several hours running Apple H/W diagnostics, booted into Recovery Mode and ran Disk Utility on both my Macintosh HD and Time Machine backup disks;. No H/W errors or disk errors were reported.

I then used Recovery Mode to reinstall my last Time Machine backup image just before I installed the last Security Update, and now everything is operating normally again.

I have NO third party S/W installed on my iMac -- I have no idea why this particular update "bricked" my system.

The Same issues here on 2019 21.5" iMac, basically unusable from being so slow. Went back to prior the Security Update 2020-005,and all speedy again, So no doubt something really wrong in that update.

Yes, 2020-004 included all previous updates. Safari 13.1.2 was released after that.

It's in the list here https://support.apple.com/en-us/HT201222 on 15 July 2020, and details here https://support.apple.com/en-us/HT211292

Apple have now withdrawn the 2020-005 update (and Safari 14.0) that's why you don't see it any more. No doubt they will release a fixed version at some point in the future, I think next time I'll wait for others to try it first :)

Looks like 2 updates came out tonight.

also, here is a great resource page

https://mrmacintosh.com/mojave-2020-005-security-update-causing-major-problems-updated/?utm_source=rss&utm_medium=rss&utm_campaign=mojave-2020-005-security-update-causing-major-problems-updated

Yes, 2020-005 Security Update is back together with 10.14.6 Supplemental Update which apparently contains Safari 14.0 and fixes for all previous issues.

More details at https://mrmacintosh.com/10-14-6-supplemental-update-safari-14-released-to-fix-previous-issues/

No reports of any problems yet but I'm going to wait until next week to install those updates.

Interesting enough, my 2ghz MacBook Pro (late 2013) 8GB ram running High Sierra apparently ran the same security update and is running just fine. Clearly the issue is specific to the Mojave platform. Either way - I turned off the security updates as well on my Pro. Yes i know HS is old, but it's stable... and still runs my non-subscription CS suite which I spent big $ on.

Let me ask you, we’re are you seeing these system error reports? I will go look on my system if you tell me. I don’t remember how to find them.

Also I wonder if you have a problem playing music through iTunes?

Does Siri work for you?

Can you access the Sound preference pane in your System Preferences?

Can you create a new user and see it inside the User&Group pane of the System Preferences?

I can’t do anything of these things anymore since I installed that Security Update.

Hi again. I did all you suggested: installed original Mojave, installed update 2020 -004.

All went well, thank you very much.

Then I ran Software Update. All I find is - Safari 13.1.2 which I will install. But I can't find it in the list of updates in the Apple website. Could be I'm blind though.

QUESTION: there were no other updates. Is this because, when I re-installed Mojave, all updates since 2015 are automatically included? Seems logical to me. BUT then, why is this Safari 13.1.2 showing up as a found update? Why is the dreaded 005 not showing up?

Sorry, that was two questions. I hope they're the kind of questions that get answered here. I'm used to going merrily along with a problem-free iMac since 2007 so Ive been lulled into to being a naive user. (I bought a new one in 2016 but the old one - Tiger - still runs better....)

So, you fixed your problem? I installed last night and today my system is totally crippled. So you rebooted from Time Machine.... Did you lose data?

Thanks! I will do this.

The biggest question.... does the supplemental update fix damaged systems?