Locate the RA Agent's trace log (RA_TRACE_xx.TXT) and examine for this message in "STACK TRACE" section:
java.lang.NumberFormatException: For input string: "version.txt"
This was a very unusual issue that does not occur often. The solution is to delete everything under the "cache" directory, the directory is located in the root RA Agent directory.
<baseDirectory>/cache <--- Delete everything under this directory, DO NOT delete the directory itself.