Please provide better explanation of "trigger file does not exist. exiting quietly." error message

[voxik]

On 2022-08-12, I was trying to upgrade fully updated but EOL F33 system to something more recent, such as F35/F36. However, the upgrade failed with "trigger file does not exist. exiting quietly." error message very likely coming from here:

https://github.com/rpm-software-management/dnf-plugins-extras/blob/cef43db2014673c528a2f13eaf1c72ecef5f0734/plugins/system_upgrade.py#L534

But I am quite unsure, what it does mean and what should I do about to proceed further. Therefore could you please provide some helpful message of what is really going on? This one is useless.

[nikunjbhatt]

I am seeing the same error when trying to upgrade from v35 to v37. Nobody knows which file is called the trigger file?

See the code at the line number 533 https://github.com/rpm-software-management/dnf-plugins-extras/blob/cef43db2014673c528a2f13eaf1c72ecef5f0734/plugins/system_upgrade.py#L533 in the file and above the line pointed out by @voxik ,
So, what is the value (file name?) of self.magic_symlink?

How to solve the error?