When the map control makes requests to the MapServer/export endpoint it uses 2083 characters as the maximum URI length before switching from GET to POST. The plugin/browser prevents requests at 2048 characters so sometimes you can't get a map image.The behavior is pretty simple to replicate:1. Start with the ESRI API sample http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#DynamicMap. 2. Artificially inflate the list of visible layers by adding duplicate layer IDs. This will make your request really long. You'll probably need about 600 layer IDs. It's low tech but effective.<esri:ArcGISDynamicMapServiceLayer ID="MyLayer"
Url="http://maverick.arcgis.com/ArcGIS/rest/services/World_WGS84/MapServer"
VisibleLayers="1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1....." />
3. Watch the requests in Fiddler and you'll see your GET request URLs approach 2048 characters, and then the map will go blank and you won't see any requests in Fiddler.4. Keep adding layers and checking Fiddler.5. Eventually the map image will appear and you'll see POST requests in Fiddler. Presumably we have now hit the 2083 character limit.This is quite important for our customers that use WKT spatial references. They frequently hit this limit.Thanks,--Ryan
