CUPS disappearing print jobs, bad file descriptor, and unsupported charset

[Polytropon]

The following question is redarding a Canon Lasershot printer using
the ccp "compiler" via Linux ABI which has stopped working with
CUPS, suddenly. The following messages are stored in the error
file /var/log/cups/error_log:

	X [12/Feb/2017:12:17:14 +0100] kevent() returned Bad file descriptor

What is this message about?

	E [12/Feb/2017:12:18:43 +0100] Returning IPP client-error-not-possible for Cancel-Job (ipp://localhost:631/printers/Lasershot) from localhost

When a file is printed, CUPS accepts it, then it disappears and
the printer is always "idle". Of course the printer is both ready
and accepting jobs. From "localhost:631" the test page can be
selected, it won't print anything, but also not show any error
in the printer overview or detail page. The command "lpstat -a"
lists the printer correctly.

	E [12/Feb/2017:12:18:45 +0100] Unsupported character set "iso-8859-15"

Nothing on the whole system defines iso-8859-15, it is a UTF-8
system, configured that way in all relevant configuration files.

	E [12/Feb/2017:12:18:45 +0100] Returning IPP client-error-bad-request for CUPS-Get-Printers (no URI) from localhost

No idea what this means. As I said, there are no error messages
in the web page or in the log file that indicate an error with
converters, filters, or backends.

	W [12/Feb/2017:12:18:57 +0100] [Job 2216] The printer is unreachable at this time.

The last message is printed every 30 seconds.

There has not been an update for some time now, and the last time
I checked, the printer worked, both from LibreOffice (it is also
configured in "spadmin.bin") and from "localhost:631" / test page.



What could cause CUPS's hick-ups? I didn't change anything... ;-)



-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...