FULL PRODUCT VERSION :
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.15063]

EXTRA RELEVANT SYSTEM CONFIGURATION :
64-bit version of Windows

A DESCRIPTION OF THE PROBLEM :
Calling javax.annotation.processing.Filer.getResource for a resource that does not exist now throws a NoSuchFileException. Previously it threw a FileNotFoundException.

This means following code, which was valid in Java 8, now no longer catches the appropriate exception, but reports an error:

      try {
        String service = ...;

        //check whether the file was already written before
        FileObject f = filer.getResource( StandardLocation.CLASS_OUTPUT, "", "META-INF/services/" + service );

        //process the previous content and merge it with the new annotation information
        //...
      } catch ( FileNotFoundException x ) {
        // doesn't exist, so there is nothing to merge. Just write the new information
      } catch ( IOException x ) {
        processingEnv.getMessager().printMessage( Kind.ERROR, "Failed to load existing service definition files: " + x );
      }

REGRESSION. Last worked in version 8u131

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
- Create an annotation processor that uses the technique above
- Compile a project using that annotation processor

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No errors are reported, the code just remains working as it was.
ACTUAL -
The annotation processor now reports an error instead of catching the correct error

ERROR MESSAGES/STACK TRACES THAT OCCUR :
compile_samples:
    [mkdir] Created dir: C:\Project\distrib\samples\build_files\classes
    [javac] Compiling 2740 source files to C:\Project\distrib\samples\build_files\classes
    [javac] error: Failed to load existing service definition files: java.nio.file.NoSuchFileException: C:\Project\distrib\samples\build_files\classes\META-INF\services\samples.common.Service

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Make the annotation processor also catch the NoSuchFileException.

This is only feasible if you have control over the source code of the annotation processor.