Unable to launch an app installer ...

Have you tried ctrl-clicking on the installer and selecting Open, then Open again on the confirmation dialog?

This is irrelevant to the problem, but I'll use it as an example to explain why you got those errors.

SUDO xattr -rd com.apple.quarantine /Applications/Install USA19H Driver.app

Password: XXXXXXX

xattr: No such file: /Applications/Install

xattr: No such file: USA19H

xattr: No such file: Driver.app

Unix shells treat white space as argument delimiters. In your example, you sent three different paths to the xattr command, not one. When there are spaces in the path, you need to escape them with "\ " or enclose the entire string in double quotes.

SUDO xattr -rd com.apple.quarantine /Applications/Install\ USA19H\ Driver.app
SUDO xattr -rd com.apple.quarantine "/Applications/Install USA19H Driver.app"

I had the same issue with installing the Tripp Lite driver on Big Sur and the following command (from the Terminal window) fixed it:

chmod -R 755 /Applications/Install\ USA19H\ Driver.app 

This changes the file permissions inside the installer, and then I was able to run the installer from the Applications folder.

It's possible that there's a 32 bit component in the installer that won't run on Big Sur. You can check that by downloading and running the free GO64 app. It will show you which are strictly 32 bit, 64 bit and those with a 32 bit component.

If the installer is an installer package like this:

you can use the demo version of Pacifist to open and instal the contents of the package.

Control-clicking the app does not change anything.

Then Tripp Lite needs to update their installer.

As for the Terminal syntax, it does not change anything either.

Yeah, that's what I meant by it being irrelevant. I was just explaining what you were doing wrong in case you ever need to use the command line again.

Robert Lesperance wrote:

With all the serious tricks I tried (see above), what do you, as an expert, think could explain why I am not able to launch an app ?

Contact the people who created Tripp Lite and ask them why their installer doesn’t work.

Hi mighty_worm,

Thanks for the info. Quite special to receive this information from a Level 1 user. I would still appreciate to have a better understanding of this command, it's precise scope and security related consequences. I am only a Terminal novice.

I would appreciate a confirmation from more experienced users before trying it.

If it works, what can explain why Tripp Lite has formatted the app's permissions the way they did and why weren't they able to help me ?

Thanks again for dropping that command to my attention.

Can I ask why changing the permissions from the info window did not work ? I tried that myself. How is it different from the chmod command ?

The GUI interface prevents some actions in certain locations. Apple did not extend those restrictions to the command line.

I don’t think there is any difference. I believe Finder uses chaos, also. However, it can choose not to execute the chmod command.

I don’t know what the Mode of that installer was before it was fixed. It should have been owned by whatever user saved it into the Applications folder.

I’m not sure why an app installer was in the Applications folder in the first place. Apple does it with OS installers, but it also cleans up after itself.

Did you change owners? What was the owner before you changed it and when did you do that? chmod only changes the mode, not ownership.