How do I fix "Construct 3 Failed to open project. Check it is a valid Construct 3 single-file" error

Hello, recently Construct 3 updated to r317 version, and the next day the following error started to appear every time I try to open my project: "Construct 3 Failed to open project. Check it is a valid Construct 3 single-file (.c3p) project."

This is a 3 years project, and I always kept 3 different backups of the project, one in the cloud, one in the dropbox, and one as a local file. After the update, they all fail to open. I already tried to go back in some old versions of Construct 3, but it keeps giving the same problem.

Does anyone know how I can resolve this? Please?

That's it! It has a folder called "A.R.M.A." and it is an invalid folder. The question now is, how can I find and rename this folder? I turned the c3p project into a zip and looked for that folder, I didn't find it.

But I'll go ahead, thank you very much, I'm a little calmer now haha

OK, I FOUND IT, IT'S WORKING! Thank you so much! :D