Pavonis Interactive Forums

This is really a big let down. Any way to recoup from that?

And if not, is that common, because really, it forbid ironman in this case.

I don't know if it is common but it did happen in Vanilla and might not even be caused by XCom itself. Lots of things can cause a file to get corrupted on a computer.
Try to keep back-up copies of your IM save so in case something like this happens, you won't have to restart everything. Hopefully reverting to a back-up is annoying enough that you won't be tempted to save-scum your Ironman game cause it's entirely possible
Alternatively if you can resist reloading when something bad occurs, just save as usual and play an "Honestman" game. Truly the only difference is that you need better self discipline to play Honestman.

I don't think you can do anything once your save refuses to load if you don't have a backup