[ESS] .Rdata not loading

[Rich Shepard]

I use R with emacs and ESS. Each time I finish with a session I save the
image. Today when I invoke ESS the saved image did not load and manually
running 'load('.RData') fails:
> load('.RData')
Error in load(".RData") :
   ReadItem: unknown type 0, perhaps written by later version of R
>

This has not happed before.

Installed is R-4.1.2-x86_64-1_SBo and in the PWD I see:
$ ll .RData*
-rw-r--r-- 1 rshepard users 28074080 Dec 22 15:32 .RData
-rw-r--r-- 1 rshepard users      134 Nov  4 14:57 .RDataTmp
-rw-r--r-- 1 rshepard users        0 Nov  4 14:57 .RDataTmp1

What might be keeping .RData from loading?

How do I load it?

TIA,

Rich