Hi Claus,
Just a thought...
Did you restore to an alternate path and end up with a long path length - i.e. longer than 260 characters?
If so, then this article may be of relevance.
https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry
try and access the file using the "\?" prefix. For example, "\?\D:\very long path".