Failure to load cffi (again): unable to find maven (again)

Earlier today I was able to load cffi by renaming mvn.cmd to mvn.bat.

Later on, I am unable to, and I would appreciate a fresh pair of eyes.

(ABCL/Java info:
C:\Users\977315>java -jar "c:\mv-program-files\abcl-bin-1.4.0\abcl.jar"
Armed Bear Common Lisp 1.4.0
Java 1.8.0_112 Oracle Corporation
Java HotSpot(TM) 64-Bit Server VM
Low-level initialization completed in 0.243 seconds.
Startup completed in 3.812 seconds.
Loading C:\Users\977315\.abclrc completed in 13.729 seconds.)

The error seems to happen in abcl-cffi.lisp.
mvn.bat is visible:
(uiop/run-program:run-program '("where" "mvn.bat") :output :string) gives
"C:\\Program Files\\apache-maven-3.3.9\\bin\\mvn.bat
"
NIL
0

I don't know how to narrow down the search for the culprit.  It makes me
think
that maybe the error message is not correct - that there is a different
underlying
cause.  Is there some direct way I can test maven+aether?  I now next to
nothing
about Java, and looking at abcl-cffi, I did not find anything obvious.

Thanks for your help and patience,

Backtrace follows.

 CL-USER(4): (asdf:load-system :cffi)
; Compiling C:/mv-program-files/my-lisp-libraries/cffi/src/cffi-abcl.lisp
...
Using probed value of abcl-contrib:
'C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar'.
Added
jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/quicklisp/ to
ASDF.
Added jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/mvn/ to
ASDF.
Added jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/jss/ to
ASDF.
Added jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/jfli/
to ASDF.
Added
jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/asdf-jar/ to
ASDF.
Added
jar:file:C:/mv-program-files/abcl-bin-1.4.0/abcl-contrib.jar!/abcl-asdf/ to
ASDF.
java.lang.ExceptionInInitializerError
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown
Source)
        at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
        at java.lang.reflect.Constructor.newInstance(Unknown Source)
        at java.lang.Class.newInstance(Unknown Source)
        at
org.armedbear.lisp.FaslClassLoader.loadFunction(FaslClassLoader.java:130)
        at
org.armedbear.lisp.FaslClassLoader$pf_get_fasl_function.execute(FaslClassLoader.java:165)
...
        at org.armedbear.lisp.LispThread.execute(LispThread.java:832)
        at org.armedbear.lisp.Lisp.evalCall(Lisp.java:582)
        at org.armedbear.lisp.Lisp.eval(Lisp.java:540)
        at org.armedbear.lisp.Lisp.progn(Lisp.java:709)
Caused by: org.armedbear.lisp.Go
; in (EVAL-WHEN (:COMPILE-TOPLEVEL :LOAD-TOPLEVEL ...) ...)

; Caught SIMPLE-WARNING:
;   Unable to locate Maven executable to find Maven Aether adaptors.

jnaASDF could not load  because Java exception
'java.lang.ClassNotFoundException: com.sun.jna.Native'..
#<THREAD "interpreter" {49B3491F}>: Debugger invoked on condition of type
JAVA-EXCEPTION
  Java exception 'java.lang.ClassNotFoundException: com.sun.jna.Native'.
Restarts:
  0: RETRY                         Retry completing load for
#<ASDF/SYSTEM:SYSTEM "jna">.
  1: ACCEPT                        Continue, treating completing load for
#<ASDF/SYSTEM:SYSTEM "jna"> as having been successful.
  2: RETRY                         Retry compiling
#<ASDF/LISP-ACTION:CL-SOURCE-FILE "cffi" "src" "cffi-abcl">.
  3: ACCEPT                        Continue, treating compiling
#<ASDF/LISP-ACTION:CL-SOURCE-FILE "cffi" "src" "cffi-abcl"> as having been
successful.
  4: RETRY                         Retry ASDF operation.
  5: CLEAR-CONFIGURATION-AND-RETRY Retry ASDF operation after resetting the
configuration.
  6: TOP-LEVEL                     Return to top level.