If you have setup cluster and tried to use charting in ColdFusion 8/9/10, sometimes you would have received “Image Expired” message instead of showing the chart.
Charting engine runs into this problem for two reasons.
1. The scripts generated by the designer use indirect method for image retrieval, meaning that the image is
produced during page processing and is placed in cache to be retrieved by the browser.
After some period of time depending upon cache settings the image is destroyed. “Image Expired” message
tells you that the image requested by the browser is not in the server cache.
To fix this issue you might want
to change cache settings(webcharts3D.xml under cfusionlib).
2) In some cases the reason is that one component is uesd to create the image, but another component is used to retrieve it.
In ColdFusion cluster’s case exactly this is what it happens when sticky sessions are not enabled.
So, make sure that you enable sticky session so that the a particular request comes and is servered from the same server.
After enabling sticky session make sure to restart the web server and ColdFusion server.
Hope this is helpful.