Can't view demos.

Hi, I am trying to view demos and keep getting this error:

Gmod also crashes sometimes when I try to view the demos.

If anyone knows what’s wrong or has any suggestions on how to fix it, then please tell me.

Old demos may no longer work. ( i.e. Demos recorded in old versions of Garry’s Mod )

Does this mean that the demos can’t be viewed again, or is there a way that they can be viewed?

It means that those demos can’t be viewed again.