<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">Hi there,</div><div class=""><br class=""></div><div class="">I am trying to transition to using PyNGL (using Jupiter Notebook, Python v3.7.3) on my Mac (Mojave 10.14.5).</div><div class="">I am just trying to create simple plots (code below, mostly taken from the examples online. When I run the script first, it works fine and the pdf is created exactly as advertised. All the relevant modules are loaded.</div><div class="">However if I re-run the plotting section of code in the Notebook, I get this error:</div><div class=""><br class=""></div><div class=""><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:["Error.c":406]:ErrorInitialize:Only one instance of ErrorClass is supported</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to initialize layer-Can't Create</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Error Creating ErrorClass object</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to initialize layer-Can't Create</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to initialize layer-Can't Create</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:_NhlCreate:Unable to access "default" App object</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:_NhlCreate:Invalid Parent id #-4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:NhlGetValues:PID #-4 is invalid</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:PID #-4 can't be found in NhlSetValues</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">warning:maximize_plots: Invalid workstation. No plot maximization can take place.</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:NhlDraw: Invalid Layer Id: -4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to update Workstation with PID#-4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to clear Workstation with PID#-4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:NhlDraw: Invalid Layer Id: -4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to update Workstation with PID#-4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to clear Workstation with PID#-4</span></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;">fatal:Unable to Destroy (Bad PID#0)</span></div></div><div class="" style="margin: 0px; font-stretch: normal; font-size: 11px; line-height: normal; font-family: Menlo;"><span class="" style="font-variant-ligatures: no-common-ligatures;"><br class=""></span></div><span class="">I can only get the figure again, if, in the Kernel menu, I ‘restart and run all’. It seems to be a problem with the graphics? I have xQuartz installed. From a similar topic I found online, they removed Ngl.end() at the end, however that doesn’t work for me.</span><div class=""><span class=""><br class=""></span></div><div class=""><span class="">Thanks,</span></div><div class=""><span class=""><br class=""></span></div><div class=""><span class="">Mark</span></div></body></html>