[djslater107]

It does mean that this particular version of your project is corrupt. Typically this happens when you delete an object, a parameter or a variable value that wants to use it someplace else in the program and do not go back to where that element was being used and reset it. Alice tres to prevent this with warnings, but it does not cover every contingency. Once you save the program and quit Alice, Alice is unable to reopen the program because of the missing element.

However, both Alice 2 and Alice 3 have backup systems. In Alice 3, automatic backups start the first time you save your project, and you will find a backup folder in the same location as where you were saving your file. The file names are timestamps, and so you will want to go back through the previous versions until you find one that will open. You will have lost some work, but at least not all.

The Alice 2 system is not quite so automatic, As long as you save your project every time you are prompted in Alice 2, which occurs every 15 minutes or so the backup folder. located where the file is being saved, you will have copies of the 5 previous versions of your program. If you have been ignoring those save messages, you may not have a useable backup.

Best of luck.