I am getting this exact error as well.
Opened Cakewalk by Bandlab 15min ago
Was alerted to an upgrade in the lower right corner
Began that process
Closed Cakewalk
Continued that process
Got the "Unable to register the DLL" error above.
Now I can't access any version of the software.
When I try, I get:
"The code execution cannot proceed because libmp3lame.DLL was not found.", and then
"The code execution cannot proceed because sndfile.DLL was not found.", and then
"The code execution cannot proceed because lame_enc.dll was not found."