I've identified the CL which caused this issue:

https://chromium-review.googlesource.com/c/chromiumos/platform2/+/1053426

The directory "/run/ippusb" which contains the socket used for ippusb printing is not being mounted. I have tested a change which mounts this path as well and it fixes the issue.

+kalin@ - FYI. We're working on getting a more automated test in place for this, but wanted to make sure your team is aware in the meantime.

Does it happen with any USB connected printer, and any of the cros platforms?

Should also print dialog for auto-discovered USB printers be affected?

kalin@ - This is specific to the IPP over USB workflow (not all USB connected printers).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/e694deb429ac85bd0bfbb9f1454b03927809b480

commit e694deb429ac85bd0bfbb9f1454b03927809b480
Author: David Valleau <valleau@chromium.org>
Date: Wed Aug 01 21:52:29 2018

debugd: Adding /run/ippusb to the mount namespace

Since /run/ippusb was not included in the mount namespace, ipp-over-usb
printing was failing as debugd is unable to access the socket found in
the directory.

BUG= chromium:869223 
TEST=Tested manually on device

Change-Id: Ib1e2fbbb0892e798929aad29626df78eb95d52c9
Reviewed-on: https://chromium-review.googlesource.com/1155968
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Valleau <valleau@chromium.org>
Reviewed-by: Sean Kau <skau@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

[modify] https://crrev.com/e694deb429ac85bd0bfbb9f1454b03927809b480/debugd/src/main.cc

I have tested that these changes on one of the latest images (R70-10944.0.0) from Goldeneye and everything works correctly.

If possible I would like to have them picked back into M69 as they fix crashes that users would experience when trying to print. These are small changes that should not have an impact on any other systems.

This bug requires manual review: M69 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), kariahda@(iOS), cindyb@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/fcf4ee1e3614bb8fca1f5dd2c19326d1c56e7e1a

commit fcf4ee1e3614bb8fca1f5dd2c19326d1c56e7e1a
Author: David Valleau <valleau@chromium.org>
Date: Thu Aug 09 22:33:21 2018

debugd: Adding /run/ippusb to the mount namespace

Since /run/ippusb was not included in the mount namespace, ipp-over-usb
printing was failing as debugd is unable to access the socket found in
the directory.

BUG= chromium:869223 
TEST=Tested manually on device

Change-Id: Ib1e2fbbb0892e798929aad29626df78eb95d52c9
Reviewed-on: https://chromium-review.googlesource.com/1155968
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Valleau <valleau@chromium.org>
Reviewed-by: Sean Kau <skau@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
(cherry picked from commit e694deb429ac85bd0bfbb9f1454b03927809b480)
Reviewed-on: https://chromium-review.googlesource.com/1169924
Commit-Queue: David Valleau <valleau@chromium.org>

[modify] https://crrev.com/fcf4ee1e3614bb8fca1f5dd2c19326d1c56e7e1a/debugd/src/main.cc

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

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For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot