I get this message (version 23.8.0.30) in 32-bit Sonar but not 64-bit when I go to Help/Documentation.  I have tried reinstalling, rebooting, etc.  Any advice?

This error is caused when attempting to open an old local help file in 2017.08.
 
Copy the SONAR.chm from the 64bit installation to the 32bit installation or
Run the Local Help installer at the command line or from the Command Center with the Verbose Install option enabled selecting the 32bit option.
 
IOW, when running both 32 and 64bit versions of SONAR make sure all the parts of both installs get updated. This takes two passes with each installer, one for the 32bit install and one for the 64bit install.

I always do update both 64-bit and 32-bit when Sonar is updated, but I didn't realize that the help file needed updating in both.  My 32-bit help file was from 2016!  Thanks!