What happened to my Grasshopper file?

My GH file was opened successfully yesterday. But today when I opened it, it said ‘IO generated 1 message’,IO2
and a ‘grasshopper archive messages’ exist.
When I clicked close then the message window disappeared.

This is not necessarily a Ladybug Tools question but in most cases a warning like this happens when you have saved the Grasshopper file with a more recent version and then trying to open it with an older version. I believe the error message is different from what you get though. You should post this question to the McNeel forum.

Thanks for your help @mostapha