Hi, I use R in a terminal environment on a linux box, using X11 for graphics, often tunnelled to the terminal I'm using. When an internet connection dies (say, if the ssh connection dies when forwarding), R usually gives a scary warning like "Error: X11 fatal IO error: please save work and shut down R." That's all well and good. Then, if I ignore it and try to plot() something, R dies quite ungracefully, producing (e.g.) something like this: R: ../../src/xcb_io.c:385: _XAllocID: Assertion `ret != inval_id' failed. Aborted ...and returning me to the shell. If I have not saved, I have lost my work. Clearly, this is my fault--I ignored the warning. However, I just had the above happen to me without my being warned...I lost some data, but not a lot. I am working on creating a reproducible case currently. That said, in the meantime, I would suggest a broader fix. I'm sure we can agree that R aborting due to failed assertions like this are pretty unfortunate. In the case of X11 failures like this, however, there is an alternative: Print an error message and take a preventative action. "Error: X11 fatal IO error: X11 device disabled." ...and then call dev.off(). Indeed, if I just run dev.off() when I see this error, nothing about R seems corrupt at all. I can start a new X11 window with, X11("localhost:10") and things (such as plotting) function fine. Cordially, Adam