Exception by BufferedOutputStream.flush: Attempt to invoke virtual method 'void java.io.OutputStream.write(byte[], int, int)'

Question

An app gets the following exception occasionally:

Stack trace:

java.lang.NullPointerException: Attempt to invoke virtual method 'void java.io.OutputStream.write(byte[], int, int)' on a null object reference
    at java.io.BufferedOutputStream.flushInternal(BufferedOutputStream.java:185)
    at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:85)

from:

bufferedOutputStream.flush()

I assume it is not because bufferedOutputStream is null, but something else. If may understanding correct? If so, what is it?

bufferedOutputStream.write(byteArrayData, iOffset, iDataLength);
bufferedOutputStream.flush();