I’ve got a printer connected on my Windows machine and it’s shared so I can print from my Ubuntu Intrepid machine as well using Samba. It works pretty well. I usually only print from OpenOffice 3 but today I had to print an email (Claws mail) and it failed. I got the Printer selection box but when I clicked on print an error message popped up, “Can’t prompt for Authorization”. I checked my printer settings and everything looked fine, so I tried again, another error message popped up: “Too many failed attempts”.
After sending an email to the Claws Mail list, Colin Leroy pointed out it could be a bug in GTK as I also couldn’t print from Gedit. I did some searching on the Internet and found several reports similar to mine but no solution.
I started to do some researching on my laptop and I found a work around to solve the problem.
I started by checking my logs and in the /var/log/cups/error_log I saw this message “Print-Job: Unauthorized”.
Checking the cups configuration file printers.conf, which holds the definition of your printers.
These are the first few line of my printer definition of the printer I had a problem with.
<DefaultPrinter tp0> AuthInfoRequired username,password Info Canon_PIXMA_iP8500 Location DeviceURI smb://Guest@Home/Desktop/CanonPIX
It looks like cups requires authentication as username and password. Unfortunately you can’t enter a password because of a bug somewhere which throws the error message “Can’t prompt for Authorization”.
Now the DeviceURI line already has a username build in to it, Guest. My Guest doesn’t require a password, in other words cups doesn’t have to ask me for a username and password.
Here’s my working configuration:
<DefaultPrinter tp0> #AuthInfoRequired username,password Info Canon_PIXMA_iP8500 Location DeviceURI smb://Guest@Home/Desktop/CanonPIX
This works fine for me.
I haven’t tried this but I’m pretty sure if you don’t have a user on your URI line you can just add it and comment out the AuthInfoReuired line. And if your user needs a password, you could add this as well like this: smb://Bob:NotSoSecret@…
I understand it could be a security issue in a business environment but it’s perfectly fine here at home.








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Thanks! This seems to have worked at my office. You are the healer of many headaches.
@ Blaise
You’re welcome.
Hmmm, maybe I should change the name of the blog to Aleve or Tylenol
The Problem for me is that the /etc/printers.conf is recreated everytime my printer (or server?) restarts and the “#” is gone
Try the following:
Modify your printer settings through the CUPS webinterface http://localhost:631/
Select Printers
Select Modify Printer
Keep clicking Continue ’till the last screen where you can only select Modify Printer
Now edit the /etc/cups/printers.conf file
Add the user on the SMB line of your printer
Let us know if that works for you.
I don’t know if I get it right.
I changed “DeviceURI smb://WORKGROUP/DiskStation/usbprinter” to DeviceURI smb://thomas@WORKGROUP/DiskStation/usbprinter
This didn’t solve the problem. I also went through the “Modify Printer” but there I only could change the path and driver.
@Thomas
What if you delete the line:
AuthInfoRequired username,password
all together?
Thanks for the swift reply. The file is recreated all the time.
The DeviceURI was changed back, too.
Printing in OpenOffice works, acroread too.
It is not working in evince or firefox.
@Thomas:
Contact me through the contact page using your email address. It will be easier to communicate through email.
Can someone please post a reply as I am still having this problem. Thank you!
-Jason
@Jason
What problem would that be?
@Peter,
The printing issues. I edit the printer.conf file by adding the comment symbol in front of the Authorization line. It changes back to what it was before. I have also copied the printer as indicated by another workaround, and it works for a few time and then I get the same error….
“Can’t prompt for authorization”
Thanks for your help.
-Jason
@Jason R.
What Distro are you using?
Do you have a local printer attached to the desktop?
There is a bug reported for this issue:
https://bugs.launchpad.net/bugs/283811
I have the same problem here.
I am using Ubuntu 8.10. The printer is connected to my windows desktop running vista 32bit ultimate.
-Jason