The application “Installer” can’t be opened. -36 error

-36 means the file became unavailable since starting to read it, can be corruption, bas cable, low USB power, etc.

-36 means the file became unavailable since starting to read it, can be corruption, bas cable, low USB power, etc.

It can also be an older incompatible format.

Refer to a similar question regarding " macOS InstallAssistant.pkg "

Thank you @BobHarris

Specifically >> If you get the package directly from Apple, then yes it is a legitimate way to install macOS.

So the question becomes, are the .DMG and .PKG files coming Directly from Apple ?

Have you repaired the drive?

Also get Drive DX to test the health of the drive.

To get the Full Installer of Sequoia 15.5

We used to be able to run the below Terminal command

softwareupdate --fetch-full-installer --full-installer-version 15.5

Caveat - Once the computer has Already installed Sequoia 15.4 and above

The above command will present as in illustration below

There has been a long discussion as to whether this is by Apple Design or an oversight

So far, there is very little information available, to confirm or refute these claims

So, in effect what you have tried to perform seems to confirm even the Pkg Installer of Sequoia is also affected by this negatively

Yes, we can see the currently available Full Versions of Sequoia

To reiterate, once Sequoia 15.4 is installed, downloading full versions thereafter seems problematic

softwareupdate --list-full-installers

Finding available software

Software Update found the following full installers:

* Title: macOS Sequoia, Version: 15.5, Size: 15283299KiB, Build: 24F74,

* Title: macOS Sequoia, Version: 15.4.1, Size: 15244333KiB, Build: 24E263,

* Title: macOS Sequoia, Version: 15.4, Size: 15243957KiB, Build: 24E248,

* Title: macOS Sequoia, Version: 15.3.2, Size: 14890483KiB, Build: 24D81,

* Title: macOS Sequoia, Version: 15.3.1, Size: 14891477KiB, Build: 24D70,

* Title: macOS Sequoia, Version: 15.3, Size: 14889290KiB, Build: 24D60,

.dmg files files from Apple

The last offering from Apple in dmg format for full version of OSX was OSX 10.12

So stop being coy and inform What dmg from Apple