I recently ran into an error condition, in which on my Linux laptop ‘Klystron’, I had pulled up a Printers List within Firefox, to Print out a Web-page. And the list of available printers kept updating, alternately with a network printer displayed as existing, and with the same printer missing, just over once per second.
I was able to get to the root of this problem.
I had recently installed the package ‘avahi-daemon’ on that laptop, prior to which that error condition did not occur. ‘avahi’ is a service-discovery daemon, which means that it scans the network neighborhood, and makes shared resources visible in the lists of GUI applications, where those resources might normally not be visible under Linux.
The cause of this problem seems to be, that if more than one resource exists by the same name, Firefox will continuously be in a state of confusion, about the fact that both resources should exist side-by-side.
For example, it is possible to have a printer named ‘PIXMA_MX922′, which is a WiFi-printer and which is therefore accessible directly on the LAN, by way of the router. It could be installed directly on all the computers by way of CUPS. But at the same time it is possible to have a server set up which is named ‘Phoenix’, the CUPS service of which has that printer installed directly, as well as having the ‘Samba server’ installed, which offers to share all the local printers as a Samba share by the same name, by default.
Next, if we have a laptop named ‘Klystron’, which is running the ‘avahi-daemon’, then according to its new discovery capabilities, there are at least two printers on the same network,
- ‘PIXMA_MX922 As installed on the LAN’ and
- ‘PIXMA_MX922 As belonging to the
As far as I can tell, the problem here is that both printers will have the same name, because the
Samba server serves it out as having the same name it had locally with its own CUPS server. And at that point, the Available Printers List belonging to Firefox becomes unstable.
There is more than one way to solve this problem.