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Exercise 6: Changing Map Projections

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Exercise 7: Troubleshooting

How to find out what broke when you get the dreaded pink map or even worse, the GeoMOOSE doesn’t load.


We need a tool that lets us see behind the scenes of what is going on in the web browser. The development team uses the Firebug add-on to the Firefox browser for troubleshooting GeoMOOSE. While most browsers now have similar tools built in, this exercise will focus on using Firebug.

  1. Open the Firefox Add-ons page:
  1. Search for the Firebug Add-on:
  1. Install the Firebug Add-on:

Troubleshooting the Pink Map

A pink map is a common error in GeoMOOSE and means that GeoMOOSE was unable to get an image from a WMS server to draw a layer. To see this, we are going to intentionally break a layer.

  1. Go to /srv/geomoose/maps/demo/parcels and edit
  2. Add an extra M to the word MAP on line 21 and save.
  3. Reload GeoMOOSE and you should see the pink screen.
  1. To see what went wrong, activate Firebug by clicking on the “bug” tool in the browser toolbar and reload the page.
  1. Click on the “Net” tab and then click “Enable”.
  1. Reload GeoMOOSE and you should see the list of resources GeoMOOSE requests from the web server.
  1. Scroll and hover over the mapserv? until you find the one that doesn’t show an image. Then right click and “Open Response in New Tab.
  1. Read the error message from MapServer.
  1. Fix the Mapfile (by deleting the extra M added in the beginning)

Troubleshooting failure to load

If GeoMOOSE fails to load completely, it is usually because of an error in the mapbook.

  1. Introduce a structrual error into the mapbook. Change <mapbook version="2.8.0"> into <mmapbook version="2.8.0">. Then reload the interface and see what it does.
  1. Look at the errors in Firebug.
  1. Restore the mapbook and reload the interface to make sure it works again.

  2. Introduce a different error the mapbook. Change the name for the natural_earth map-source so it doesn’t match the path for that layer in the catalog. I.E. change:

    <map-source name="natural_earth" type="mapserver" queryable="true">


<map-source name="natural_earth_" type="mapserver" queryable="true">
  1. Reload the interface and see what it does.
../../_images/ex7-mapbook-3.png ../../_images/ex7-mapbook-4.png