This is probably related to site isolation - we are stripping information which comes cross-process. Perhaps, we should not report any information here as a first easy step. 

Or emit this message from browser longer term. Eugene, mind taking a look?

Thanks for the report!  DevTools frontend still receives the proper error message, just doesn't render it.  I think it's unrelated to site isolation, will take a look.

Narrow bisect:
https://chromium.googlesource.com/chromium/src/+log/6c5d2a4b76447457f77207430b1b9d124f43f753..88b392acd3923b7933bf1de66cac2068b7163992

Suspect:
https://chromium.googlesource.com/chromium/src/+/848d697da0766cc108c5f869f38128b8ff52df94

 Issue 836039  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9239db0ce447d1b78fd9191b1b997604562e6879

commit 9239db0ce447d1b78fd9191b1b997604562e6879
Author: Erik Luo <luoe@chromium.org>
Date: Thu Jun 28 16:20:32 2018

DevTools: show localized error message for Network errors in Console

When migrating [1] formatting logic from ConsoleViewMessage.js to
BrowserConsole.js, we forgot to add the line that tries to show a
localizedFailDescription.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/920541

Bug:  816743 
Change-Id: Ic3e6cc49b8634a12fe8667c19fdc4623780075db
Reviewed-on: https://chromium-review.googlesource.com/1115872
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571153}
[modify] https://crrev.com/9239db0ce447d1b78fd9191b1b997604562e6879/third_party/WebKit/LayoutTests/http/tests/devtools/console-resource-errors-expected.txt
[modify] https://crrev.com/9239db0ce447d1b78fd9191b1b997604562e6879/third_party/WebKit/LayoutTests/http/tests/devtools/console-resource-errors.js
[modify] https://crrev.com/9239db0ce447d1b78fd9191b1b997604562e6879/third_party/WebKit/LayoutTests/http/tests/devtools/network/script-as-text-loading-long-url-expected.txt
[modify] https://crrev.com/9239db0ce447d1b78fd9191b1b997604562e6879/third_party/WebKit/LayoutTests/http/tests/devtools/network/script-as-text-loading-with-caret-expected.txt
[modify] https://crrev.com/9239db0ce447d1b78fd9191b1b997604562e6879/third_party/blink/renderer/devtools/front_end/browser_console/BrowserConsole.js

After the fix in #5 bakes in Canary, I plan to request a merge to 68.

This bug requires manual review: M68 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), kariahda@(iOS), bhthompson@(ChromeOS), abdulsyed@(Desktop)

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

abdulsyed@, is it possible to merge to M68?  The CL in #5 has been on Canary for a couple of days.  It only affects tests and the DevTools frontend.

Since this has been present since M66, let's just wait until M69. Do you think its fine to wait until then?

That sounds reasonable to me, since it has already been on stable for awhile.  Marking as fixed, then, unless there are objections.

It is also extra brackets on the HTTP status codes (errors). Releated to this issue.
It is not fixed in the last canary 69.0.3483.0

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Hm, #13 looks related, but a separate root cause.  Do you happen to have a URL/jsfiddle that consistently reproduces?

Here you go: https://topjohnwu.github.io/libsu/
But looks like this happens not in all cases. It can be "404 (Not found)", like normal way, or it can be only brackets, like on image higher. May be it is "empty description" or something similar?

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Thanks!  I've filed a separate report for #13 at: crbug.com/861881