Attaching file here too.

Deleted: cups_printer_error.png 125 KB

	cups_printer_error.png 125 KB View Download

How did you get this error? This assertion error is expected if the printer protocol is not one of ipp/ipps/http/https/socket/lpd/usb. See https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/printing_page/cups_printer_details_page.js?rcl=0&l=74.

Encountered that error when running ChromeOS from Linux, using one of the fake printers that show up when you search for printers (see screencast).

Deleted: printer_error.mp4 369 KB

	printer_error.mp4 369 KB View Download

Ah I see. It seems the fake printer's protocol is incorrectly initialized here: https://cs.chromium.org/chromium/src/chromeos/printing/fake_printer_discoverer.cc?rcl=0&l=69. I'll work on a fix.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5ccb4774cad17a028967e67b49a62a96d1f7af0f

commit 5ccb4774cad17a028967e67b49a62a96d1f7af0f
Author: xdai <xdai@chromium.org>
Date: Tue Oct 25 23:03:03 2016

[CUPS] Fix a typo error of the fake printer's protocol.

The typo caused "Assertion error" when viewing details of a CUPS printer.

BUG= 657672 

Review-Url: https://codereview.chromium.org/2450653003
Cr-Commit-Position: refs/heads/master@{#427522}

[modify] https://crrev.com/5ccb4774cad17a028967e67b49a62a96d1f7af0f/chromeos/printing/fake_printer_discoverer.cc

(Adding Hotlist-MD-Settings-CloudPrint for organization, though I know CUPS is unrelated)

xdai@ Trying to verify this bug. Could you provide verification steps?

Re#11: There is repro steps in comment#3. 

Verified on M62 (Chrome OS 9807.0.0, 62.0.3176.0 dev build).