Using a file containing simply:
@startuml test.png
version
@enduml
...and also every other file I've tried it with, plantuml.jar 2017.10 gives the following exception report:
(0.427 - 981 Mo) 853 Mo - Reading file: test.txt
(0.427 - 981 Mo) 853 Mo - name from block=test.png
(0.427 - 981 Mo) 853 Mo - Checking=test.png
(0.427 - 981 Mo) 853 Mo - f=test.png
(0.428 - 981 Mo) 853 Mo - Relative, so let's change it
(0.428 - 981 Mo) 853 Mo - f=c:\Users\agillesp\Documents\test.png
(0.428 - 981 Mo) 853 Mo - It's not a directory
(0.429 - 981 Mo) 853 Mo - test.png is not taken as a directory
Exception in thread "main" java.lang.IllegalArgumentException
at net.sourceforge.plantuml.SuggestedFile.<init>(SuggestedFile.java:48)
at net.sourceforge.plantuml.SuggestedFile.fromOutputFile(SuggestedFile.java:74)
at net.sourceforge.plantuml.SourceFileReader.getGeneratedImages(SourceFileReader.java:180)
at net.sourceforge.plantuml.Run.manageFileInternal(Run.java:417)
at net.sourceforge.plantuml.Run.processArgs(Run.java:328)
at net.sourceforge.plantuml.Run.manageAllFiles(Run.java:298)
at net.sourceforge.plantuml.Run.main(Run.java:158)
But it works fine with 2017.09 and earlier versions