Need to recover LibreOffice base file

I thought I had saved the odb file when exiting LibreOffice. Now when I try to open it I get the following error message:

LibreOffice Version Incompatibility Incorrect file version.

Therefore all my work has been lost. Not a good start.

What if anything can be done about it?

I cannot answer your questions, but since it is so particular (and apparently you fear about your data), I suggest you to raise this issue at Alternatively you can submit a bug (but this likely will require to attach your .odb file.)