Installing Software in Qubes from .deb / .rpm

[deeplow]

@rooftop also shared a similar answer:

Install Discord on debian template from .deb

The message is because the user _apt can’t access the .deb file as the parent directory /home/user is only accessible by the user user. If you were to copy the .deb file to /tmp (for example) and install it from there you would not get the message. However, I believe the package should have installed correctly even with the warning message. Did you try running it?