Windows lose focus after Big Sur upgrade.

Try:

• Restart your Mac
• When you restart, hold down the <Shift> key until you see the login window (restarting will likely take a while longer, you will have to endure keeping the <Shift> depressed the whole time until you see the log in window).
• You are now logged in in safe mode (it says so in RED in the top right-hand corner of the menu bar)
• Try to reproduce the problem
• If it does not occur again, a conflicting module of a third-party app was not loaded
• Restart again, this time don’t hold down the <Shift> key
• When you are logged in, does the problem persist?

This began happening to me when I installed the beta of Logitech's Logi Options+. Uninstalling it solved the problem. And as far as I could see, when it came to managing my MX Master 3 mouse, Logi Options+ only had a somewhat cleaner interface compared to Logi Options. No changes to functionality and no obvious improvement to performance.

If you haven't tried it already, I suggest trying the python script from the thread linked by Ignace above. For me, that script identified the offending process as CUH, the Corel Update Helper. I removed that app and I have not seen this issue since then. Overall it looks like different people have different applications that trigger this issue. One thing I did notice was the CUH process was not responding when I checked the activity monitor. It is possible that hung processes are contributing to the issue regardless of what that process is. If you're still having a difficult time identifying the cause on your machine, you might want to look there to see if anything stands out.

Yes. Below is a python script. Run this in a terminal window. When this issue happens look at the terminal window. This script will tell you which task was the last one to get focus. That is the one causing the problem. Stop running that program and this issue goes away.

#!/usr/bin/python

# Prints current window focus.

# See: https://apple.stackexchange.com/q/123730

from AppKit import NSWorkspace

import time

workspace = NSWorkspace.sharedWorkspace()

active_app = workspace.activeApplication()['NSApplicationName']

print('Active focus: ' + active_app)

while True:

time.sleep(1)

prev_app = active_app

active_app = workspace.activeApplication()['NSApplicationName']

if prev_app != active_app:

print('Focus changed to: ' + active_app)

Seems like, it is a mac os issue.

I occurs with Big Sur 11.4 but not with 11.6

Try updating OS.

Try reducing the Trackpad Tracking speed in System Preferences, as it may be overly sensitive at higher settings. My Air has its Trackpad setting at:

and if I happen to have a heavier weight, long sleeve garment on, the cuffs will drag across the Trackpad, and send my cursor elsewhere from where I am typing. Roll my sleeves back and its a non-issue. I may need to further reduce my Tracking speed.

Ok, after a bit more sifting through the console messages and trying to reproduce and correlate when focus is lost with the messages, I may have found the cause on mine. I have a program called "Keep Drive Spinning" which is to prevent my external USB hard drive from spinning down. Every time focus was being lost, I saw an entry for that app. After killing an re-running that app, reconfiguring it's drive wake settings and such, all seems to be well for me. This is such a unique thing, I'm sure it's not the solution for everyone else.

There is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This user tip describes what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community   

Uninstall the Norton software according to the developer's instructions. Also any other cleaning, optimizing or A/V software that might be installed.

There appears to be a procedure that will tell you which app has the focus.

I’m not fluent in Terminal but if you are you could use this:

https://apple.stackexchange.com/questions/123730/is-there-a-way-to-detect-what-program-is-stealing-focus-on-my-mac

Good luck!

For me it seems related to Microsoft Onedrive. When I quit OneDrive I don't see the issue. But, that is a critical piece of my close.

It's a know bug so report it to Apple via Feedback - macOS - Apple so that the squeaky wheel gets the grease.

What you’re saying is: there is a cause for this issue that occurs when a module is loaded that causes the behaviour.

It’s very likely an app that you use frequently that causes the issue. You would need to monitor (as would I), which app that would be. The easiest, but likely not practical in your normal workflow, way to see that is to use one app at a time and then see when the issue starts to occur again.

I’m in the same boat. I couldn’t say which app it is, or whether it’s a class of apps that uses the module, which causes the problem to occur.

I did not say: remove the app. I said: restart in safe mode, which only launches the OS and does not load other modules. When you reboot after that, that module not being loaded at startup, the problem does not occur.

There appears to be an app/procedure that allows the user to see which module steals the focus. I don’t know how to use that procedure. Once identified, killing that process in the Activity Monitor will likely stop the issue from occurring.

I’ll be happy to use my little procedure for those times the problem does occur, which is not all that frequent. That is not enough as a final solution, this is how one module is created and that has to be addressed by whomever created it.

Figure out what that module is, what app it is connected to, share that knowledge with this community and think of Jack Woltz when you write the developer responsible for creating the problem.

Yeah, it's weird. It's definitely some program or utility I'm loading at start-up (I have quite a few), since I have a separate admin account on the same machine and it doesn't have this problem. I just don't have the time to go through the process of elimination it's apparently going to take to find the culprit.

I have the same issue on my iMac where there is no pointing device for me to accidentally touch within immediate reach of my keyboard. I've tried monitoring the console to see if I can see something logging a poling interval but there's so much going on in the message console that it's really hard to narrow down exactly when the window loses focus.