This has been observed once on JDK 9 promotion b172 testing on Windows 7 x86.

Exception messages as below. Also attached the whole jtr file.
java.util.concurrent.CompletionException: java.nio.file.AccessDeniedException: RequestBodyTest.tmp
at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:632)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088)
at jdk.incubator.httpclient/jdk.incubator.http.ResponseProcessors$PathProcessor.onSubscribe(ResponseProcessors.java:129)
at jdk.incubator.httpclient/jdk.incubator.http.BlockingPushPublisher.subscribe(BlockingPushPublisher.java:47)
at jdk.incubator.httpclient/jdk.incubator.http.Http1Response.lambda$readBody$2(Http1Response.java:155)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1161)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.nio.file.AccessDeniedException: RequestBodyTest.tmp
at java.base/sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:89)
at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:103)
at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:108)
at java.base/sun.nio.fs.WindowsFileSystemProvider.newFileChannel(WindowsFileSystemProvider.java:116)
at java.base/java.nio.channels.FileChannel.open(FileChannel.java:292)
at java.base/java.nio.channels.FileChannel.open(FileChannel.java:340)
at jdk.incubator.httpclient/jdk.incubator.http.ResponseProcessors$PathProcessor.onSubscribe(ResponseProcessors.java:127)
... 5 more