We have an issue at least once to twice a month where we cannot print Ignition Labels because the CUPs server running on our Ubuntu Ignition Server is unable to find the class or printers. We've tried to remedy this by adjusting the max connections in the CUPs conf file. We've also verified that the CUPS ErrorPolicy is set to retry-job. To resolve we have to restart the Ignition Server and printing returns to normal. We are currently running Ubuntu 22.04.3 LTS and CUPs 2.4.1. Our Ignition Version is 8.1.28. CUPS is running on the same server as the Ignition Gateway. I downloaded the wrapper logs the last time this occurred and see some errors. Does anyone have any ideas for next steps for troubleshooting?
INFO | jvm 1 | 2023/08/30 00:02:25 | Caused by: java.io.IOException: error=1 running: '/usr/bin/lpr' '-PJNAPSequenceLabel1A' '-JJava Printing' '-h' '/tmp/javaprint12251040460614484698.ps' INFO | jvm 1 | 2023/08/30 00:02:25 | /usr/bin/lpr: Error - The printer or class does not exist. INFO | jvm 1 | 2023/08/30 00:02:25 | at java.desktop/sun.print.PSPrinterJob$PrinterSpooler.handleProcessFailure(Unknown Source) INFO | jvm 1 | 2023/08/30 00:02:25 | ... 47 common frames omitted