Getting com.android.volley.ServerError using the Volley library. What are some possible causes?
<p>When I make a request in Volley, I'm receiving <code>com.android.volley.ServerError</code> and response code 400.</p>
<p>I'm doing something like this (generic example code):</p>
<pre class="lang-java prettyprint-override"><code>final String param1 = &quot;...&quot;;
final String param2 = &quot;...&quot;;
// etc. 

StringRequest stringRequest = new StringRequest(Request.Method.POST, API_URL,
        new Response.Listener&lt;String&gt;() {
            @Override
            public void onResponse(String response) {
                Toast.makeText(MainActivity.this,response,Toast.LENGTH_LONG).show();
            }
        },
        new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(MainActivity.this,error.toString(),Toast.LENGTH_LONG).show();
            }
        }){
    @Override
    protected Map&lt;String,String&gt; getParams(){
        Map&lt;String,String&gt; params = new HashMap&lt;String, String&gt;();
        params.put(&quot;PARAM_1&quot;, param1);
        params.put(&quot;PARAM_2&quot;,password);
        return params;
    }

};

RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
</code></pre>
<p>What are possible causes for this?</p>