After rolling back to the previous stable Chrome OS 50, all ARC welder apps started working again.

Updated again to OS 51, and they all stopped working.

It made no difference if the apps had been installed from the Chrome store (for example, AquaMail, or VLC) or if I had converted them myself using ARC welder or ARChon packager. Must be something preventing ARC from working correctly.

I tried to capture something from the Console but all I see is:

filesystem.js:97 File system is initialized.
plugin.js:639 ARC JS Init: 80.148ms
plugin.js:648 Compositor is enabled
plugin.js:336 Plugin not ready
    $jscomp.scope.Plugin.postMessage @ plugin.js:336
    $jscomp.scope.Plugin.computeLayout_ @ plugin.js:1105
    $jscomp.scope.Plugin.doLayout_ @ plugin.js:991
    $jscomp.scope.Plugin.initializeWindow_ @ plugin.js:361
    (anonymous function) @ plugin.js:295
filesystem.js:227 ARC HTML5 FS: prefetchExtraFileMetadata_: 181.456ms

Sorry for the formatting, can't take a screenshot of the dev console and the text copy/paste messes up the formatting.

As for what you see in the actual app: the main window opens but remains white with only the app icon in the center.

When I minimize/restore/maximize the app window, the dev console only logs "Plugin not ready".

It may be the case that the ARC runtime is disabled somehow in the update.  Check chrome://extensions in developer mode to see if this is the case.  If so, a possible workaround is to uninstall all ARC apps (including ARC Welder) and install again.

I'm looking at a fix for this.

My machine shows the ARC extension as enabled. I powerwashed my machine and the problem still persisted. Reinstalling doesn't seem to help.

hmm, this is not what I expected the error would be.  Can you inspect the background page as well?  The console you pasted so far is only the app window context.  See chrome://extensions and find your app, the context with "app_main" is the background context.  Anything interesting in that console?

since you've already powerwashed your machine, another thing to try temporarily is if moving to beta (M52) or dev (M53) makes the problem go away. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/49c09c5cdf77a9f8380ce78b0e450006e22110f6

commit 49c09c5cdf77a9f8380ce78b0e450006e22110f6
Author: elijahtaylor <elijahtaylor@chromium.org>
Date: Sat Jul 09 01:06:22 2016

Make sure Shared Modules cannot be disabled

BUG= 601310 , 620091 
TEST=ExtensionServiceTest.CannotDisableSharedModules
TEST=manually disable shared module in preferences, start chrome and observe
     shared module is enabled on restart

Review-Url: https://codereview.chromium.org/2131173003
Cr-Commit-Position: refs/heads/master@{#404554}

[modify] https://crrev.com/49c09c5cdf77a9f8380ce78b0e450006e22110f6/chrome/browser/extensions/extension_service.cc
[modify] https://crrev.com/49c09c5cdf77a9f8380ce78b0e450006e22110f6/chrome/browser/extensions/extension_service_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/01925b7fc8a584580e564f8ad2c2f96a2e96441e

commit 01925b7fc8a584580e564f8ad2c2f96a2e96441e
Author: Elijah Taylor <elijahtaylor@google.com>
Date: Mon Jul 11 19:31:54 2016

Make sure Shared Modules cannot be disabled

BUG= 601310 , 620091 
TEST=ExtensionServiceTest.CannotDisableSharedModules
TEST=manually disable shared module in preferences, start chrome and observe
     shared module is enabled on restart

Review-Url: https://codereview.chromium.org/2131173003
Cr-Commit-Position: refs/heads/master@{#404554}
(cherry picked from commit 49c09c5cdf77a9f8380ce78b0e450006e22110f6)

Review URL: https://codereview.chromium.org/2136173002 .

Cr-Commit-Position: refs/branch-heads/2785@{#89}
Cr-Branched-From: 68623971be0cfc492a2cb0427d7f478e7b214c24-refs/heads/master@{#403382}

[modify] https://crrev.com/01925b7fc8a584580e564f8ad2c2f96a2e96441e/chrome/browser/extensions/extension_service.cc
[modify] https://crrev.com/01925b7fc8a584580e564f8ad2c2f96a2e96441e/chrome/browser/extensions/extension_service_unittest.cc

Note that I'm not the original submitter, just someone with what seemed the same symptoms.

I tried the dev channel as of 10am PT Jul 12 (sorry I didn't get the version). The new Google Play store feature worked fine for running android apps. I didn't try ARC Welder.

I also tried with the beta channel.
Version 52.0.2743.49 beta
Platform 8350.38.0 (Official Build) beta-channel veyron_minnie
Firmware Google_Veyron_Minnie.6588.197.0
The problem no longer occurred for me with that channel (using ARC Welder this time)

The problem came back. Looks like there is a conflict between the "CKP - KeePass integration for Chrome" extension and ARC. When I disable this extension, the ARC apps work fine. If I re-enable it, they won't start. I'm not sure if the original submitter had this extension installed as well.

ARC and this extension were coexisting happily on my system prior to the OS update that submitter mentioned.

@cdelsey, that is an incredibly interesting finding.  I just reproduced it myself by installing that extension.  No idea what's going on right now, but I will dig in.

ok, found the root cause, and will have a workaround shortly.  The underlying issue is that modifying src and type attributes of embed tags is not safe to do while the element is attached to the document: issue 629926

Guys, what an amazing find. I am the original poster but was out of the country for a few weeks, so could only follow up now.

Yes, same here: when I remove "CKP - KeePass Integration for Chrome" then my ARC apps work again. Wow!

Looking forward to a full fix, but this helps me already. I can live without CKP for now. Thank you so much!

The fix has been made to ARC and we'll be pushing it out this week if testing goes ok.

closing