GeoDjango Polygon Field ParseException
<p>I am using GeoDjango to display a form where a user can select an area on a map and name it.</p>

<p>I have the following model</p>

<pre><code>import django.contrib.gis.db.models as models    
class Area(models.Model):
  name = models.CharField(max_length=25)
  area_target = models.PolygonField(default='POLYGON EMPTY')
</code></pre>

<p>And this form</p>

<pre><code>from django.contrib.gis import forms
class AreaForm(forms.Form):
  name = forms.CharField(max_length=160)
  area_target = forms.PolygonField(srid=4326, required=False, widget=forms.OSMWidget(attrs={'map_width': 600, 'map_height': 500}))
</code></pre>

<p>The form is displayed correctly and I can select an area using the map widget, but I get the following error message when I submit the form:</p>

<blockquote>
  <p>GEOS_ERROR: ParseException: Expected 'Z', 'M', 'ZM', 'EMPTY' or '('
  but encountered : ')'</p>
  
  <p>GEOS_ERROR: ParseException: Expected 'Z', 'M', 'ZM', 'EMPTY' or '('
  but encountered : ')'</p>
  
  <p>Error creating geometry from value 'SRID=900913;POLYGON()' (Error
  encountered checking Geometry returned from GEOS C function
  "GEOSWKTReader_read_r".)</p>
</blockquote>

<p>This is how the polygon is drawn:
<a href="https://i.stack.imgur.com/CkDWV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CkDWV.png" alt="Polygon drawn with OSM Widget"></a></p>

<p>As you can see in the debug output there are no values for the edges of the polygon.</p>

<p>I am using Django 1.9.4, a postgres 9.5.1.0 DB with postgis extension and geos 3.5 as geometry backend.</p>

<p>Can someone tell me what's wrong?</p>