[cups.general] Raw printing evokes failed side-band request

[Michael R Sweet]

Kaleb Pederson wrote:
>> Kaleb Pederson wrote:
>>> I've enable raw printing by allowing application/octet-stream in mime.types and mime.convs, which worked for quite a while.  Although I'm not positive, I believe that a recent cups upgrade caused some problems with "raw" printing, even though regular printing works fine.
>>>
>>> I'm trying to print a raw file as follows:
>>> ...
>>> [Job 377] Failed to read side-channel request!
>>>
>>> (with last line above repeated about 8 times)
>>>
>>> Any suggestions on how I can isolate the problem?
>> It shouldn't cause any problems, but please do file a bug report so
>> we can eliminate the error.
> 
> Thanks Michael,
> 
> I'll do so.  Perhaps that's not the culprit, but raw printing doesn't work for me any more.  I've double-checked my configuration believe it's correct as it's basically trivial:
> 
> # grep octet-stream /etc/cups/mime.*
> /etc/cups/mime.convs:application/octet-stream  \ application/vnd.cups-raw        0       -
> /etc/cups/mime.types:application/octet-stream
> 
> Despite that, a raw printer file sent to the printer with 'lpr -o raw -P PrinterName myPrintFile.raw' results only in the printer warming up.  Cups printer logs show the print job as being completed successfully, but nothing ever prints when using raw (although it used to).  Perhaps cups is forwarding everything on correctly and is not the culprit, but I'm not sure how to identify the problem.
> 
> Any suggestions on where I can look?

What version of CUPS?

What operating system/Linux distro?

What printer?

(Some printers require a special "escape" sequence when printing
over USB, otherwise they run in an incompatible mode...)

-- 
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Michael R Sweet                        Senior Printing System Engineer