Initially presented as an issue specific to Mac OS Big Sur clients, once further reports of users of other OS's being affected it was identified as a server issue.
Restarting the MobilityPrint service on edprint.is.ed.ac.uk resolved the issue.
MobilityPrint HTTP server runtime error
Users of EdPrintPull via the MobilityPrint service
Servers / Hardware
Users setting up new connections to EdPrintPull via MobilityPrint, and some existing users submitting print jobs to EdPrintPull via MobilityPrint.
Request, Authorise and Publish
Requested by Gareth Phillips on 08-Sep-2021
Authorised by User Services
Publish to IS Website (Service Status and Alerts page):
Less than 20 reports of issues before it was resolved
Notes for future reference