Uploading file to server with multipart/form-data

I have this code:

Request restletRequest = getRequest(); HttpServletRequest servletRequest = ServletUtils.getRequest(restletRequest); ServletFileUpload upload = new ServletFileUpload(); FileItemIterator fileIterator = upload.getItemIterator(servletRequest); LOG.info("File Item iterator - " + fileIterator.hasNext()); while (fileIterator.hasNext()) { // never reached } 

With log:

[main] INFO com.xyzbackend.ServerResource - Media type - multipart/form-data; boundary=----WebKitFormBoundary5XV92DI2vfB2Z6NO [main] INFO com.xyzbackend.ServerResource - Media size - 27671 [main] INFO com.xyzbackend.ServerResource - File Item iterator - false 

The problem here is that it works on my local machine, meaning the "never reached" section is actually reached and the code executes fine. My problem is that when it gets uploaded to the cloud server (Linode with NGINX Unit server running) it starts behaving differently. The fileIterator.hasNext() is evaluated false.

Based on experience, what could be the possible causes of such weird behavior?