Help needed - failing to open complex web site 5.4 or 6

OK,
I have no idea what has happened.

I have maintained a medium sized research group website for the last N years, and have kept it in RW 5.4. Today, after a couple of months lapse, I am told that my website can’t be loaded, that RW 5.4 uses a new format that is irreversible. I have tried loading the same site in RW6 (latest) to no avail. Basically, I am completely stuck, with no way to easily recover my web site (years and years of work!). Of course, I have applied all Apple updates in the meantime (not El Capitan).

I don;t understand why a non-upgraded RW 5.4 has stopped being able to load my site (some format grumbling)
How might I get my site into RW6, if I cannot load 5.4 to export it.

All help gratefully received

Site is www.liv.ac.uk/cpr

Thanks
Rob

IIRC you need to upgrade 5.4 to 5.4.1 to be able to then open it in 6.

Thank you Dave, I recovered a version from a backup, and it seemed to open and function OK> So, I’m back to 5.4. However, I probably need to think about migration to 6. Big sigh of relief here! Rob

Just to be clear:

Open your site in Rapidweaver 5.4.1 and then SAVE IT (or save as) and then open it in Rapidweaver 6.

Thanks. I’ll do this, and make the tentative migration from a ‘comfy’ 5 to a neo-6! Rob