I found an old article that discusses this error: http://www.exelisvis.com/Support/Help... It look this error usually occurs when using Software rendering and IDLDE. If you switch from software rendering to hareware rendering (Window > Preferences > IDL > Graphics), does the error still occur? If switching to hardware rendering doesn't help with the problem, then the workaround might be to use command-line IDL instead of the IDL workbench to use the IDL Function Graphics.

I was receiving a similar error when trying to use PLOT in the Workbench.

% Compiled module: PLOTAXY.
% IDLITWINDOW::ONEXPOSE: Unable to acquire device context.
% Unable to acquire device context.
% Execution halted at: PLOTAXY 5 Z:\adit\PhD_Research\Data\Data_to_use_for_testing\ENVI_Data\Default\plotaxy.pro
% $MAIN$

Interestingly, when I followed the above, 'hardware' was already selected. I switched it to 'software' and now my plots are working.

John

Sorry, I forgot to mention that I am running IDL on a Windows 10 machine.