Hi Luca, MoI version 2.5 is an old version released 5 years ago, and I haven't been working on it for several years now. If I remember right the last OS version that runs it is 10.9/Mavericks. The current MoI version is 3.2 which has been updated recently to run on High Sierra, you would need to upgrade to that in order to run on High Sierra.

The other solution to run v2.52 would be to revert your OS to 10.9 or earlier.

- Michael

thank you for your reply.
is the upgrade discounted? I've seen that there is a cutoff date :(

Hi Luca, yes the upgrade is discounted, you don't have to pay full price again. It's the 2nd link on the purchase page.

There's only a cutoff date for an automatic free upgrade if you purchased within a couple of months of a new release. The regular discounted upgrade version does not have any cutoff date.

Thanks, - Michael