Error: invalid quartz() device size

Warning: Error in pngfun: invalid quartz() device size
  127: pngfun
  126: startPNG
  125: drawPlot
  111: 
   95: drawReactive
   82: origRenderFunc
   81: output$plot_mainplot
    1: runApp

plotOutput(outputId=”plot_mainplot”, width=”100%”) #height = “auto”

output$plot_mainplot <- renderPlot({ … })