FULL PRODUCT VERSION :
C:\Users\reynaldo>java -version
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
null pointer exception in the finally statement of the javax.imageio.ImageIO.write(ImageIO.java:1538) while trying to write an image to the file system because the stream is null.
 
      try {
            return doWrite(im, writer, stream);
        } finally {
            stream.close(); //<--- NPE here
        }

ImageIO.class full code:

    /**
     * Writes an image using an arbitrary <code>ImageWriter</code>
     * that supports the given format to a <code>File</code>. If
     * there is already a <code>File</code> present, its contents are
     * discarded.
     *
     * @param im a <code>RenderedImage</code> to be written.
     * @param formatName a <code>String</code> containing the informal
     * name of the format.
     * @param output a <code>File</code> to be written to.
     *
     * @return <code>false</code> if no appropriate writer is found.
     *
     * @exception IllegalArgumentException if any parameter is
     * <code>null</code>.
     * @exception IOException if an error occurs during writing.
     */
    public static boolean write(RenderedImage im,
                                String formatName,
                                File output) throws IOException {
        if (output == null) {
            throw new IllegalArgumentException("output == null!");
        }
        ImageOutputStream stream = null;

        ImageWriter writer = getWriter(im, formatName);
        if (writer == null) {
            /* Do not make changes in the file system if we have
             * no appropriate writer.
             */
            return false;
        }

        try {
            output.delete();
            stream = createImageOutputStream(output);
        } catch (IOException e) {
            throw new IIOException("Can't create output stream!", e);
        }

        try {
            return doWrite(im, writer, stream);
        } finally {
            stream.close();
        }
    }

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
write image to file system.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Image should be written to hard drive
ACTUAL -
NPE thrown, no image written to disk

ERROR MESSAGES/STACK TRACES THAT OCCUR :
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at javax.imageio.ImageIO.write(ImageIO.java:1538)
at server.data.Store.writeImage(Store.java:257)

REPRODUCIBILITY :
This bug can be reproduced occasionally.

---------- BEGIN SOURCE ----------
public static boolean writeImage(String id, BufferedImage img) {
boolean result = false;
if (img==null) return result;
String loc = base + File.separator + "jpg";
File dir = new File(loc);
if (!dir.exists() || !dir.isDirectory()) {
dir.mkdirs();
}
String fil = loc + File.separator + id + ".jpg";
File src = new File(fil);
try {
result = ImageIO.write(img, "JPG", src);
} catch (IOException e) {
Log.log("Error","error writing image "+ fil,e);
}
return result;
}
---------- END SOURCE ----------