I am logging into a remote Mac OSX system that is headless and I get the following error when I create a plot. What is the cause of the error? IDL> PLOT, D, D, /POLAR, TITLE = 'Polar Plot' % Loaded DLM: XML. libGL error: failed to load driver: swrast Answer: IDL is trying to use load graphics device and fails in this case because no graphics device is available. If no graphics device is available, or if the device is not working properly due to driver incompatibility, then you can set IDL to use software rendering to avoid this message. You can set this in the IDL preferences under Window->Preferences->IDL->Graphics and choose software rendering. Alternately, you can set it at the IDL command line using the IDL_GR_X_RENDERER procedure or by renaming the gl_driver.so to something like gl_driver.old. This driver is located in the \idl8.x\bin\bin.x86_64 directory (Windows), bin.darwin.x86_64(Mac OSX), bin.linux.x86_64(Linux).