After @alex answers you need to add this @Override function to your request object when adding it to the queue.
Request request = new Request( Method.GET, url, Listener listener, ErrorListener errorListener) { @Override public Map<String, String> getHeaders(){ Map<String, String> headers = new HashMap<String, String>(); headers.put("User-agent", "YOUR_USER_AGENT"); return headers; } };
To learn more about how to add this to your queries, see this StackOverflow header setting answer. - How to set up custom header in Volley request
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