This isn't a security issue and sounds like a bug in the GMail website. You can very likely fix this issue by clearing your cookies for GMail.

Try visiting chrome://settings/siteData?search=cookies and delete the cookies for mail.google.com and optionally Google.com.

(Alternatively, hit F12 to open the Developer Tools. Click the Application tab. Clear the items from the STORAGE subarea).

That's the problem: This still happens despite clearing the cache and shutting off all extensions. I can try a few more things to see if I can get it to work.

By "clearing the cache" are you including Cookies?

Are you currently logged into Chrome itself (see the top right of the window frame)?

I am clearing everything for "All of time." I'm not logged in to Chromium because I can't. If I can't log in to Gmail I can't log in to Chromium.

Try going to chrome://extensions and disabling all of the extensions. This is often the cause of things only working in Incognito as Incognito only runs a subset of extensions.

Same problem.

1. Disabled all extensions.
2. Close Chromium.
3. Restart Chromium.
4. Attempt login.
5. Get second-factor response.
6. Enter second-factor response in Chromium.
7. Get same error in Chromium: "Something went wrong..."

Thank you for providing more feedback. Adding the requester to the cc list.

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

Able to reproduce the issue on Windows 10, mac 10.13.3 and Ubuntu 17.10 using chromium dev build #68.0.3433.0.

Bisect Information:
=====================
Good build: 68.0.3420.0 Revision(556021)
Bad Build : 68.0.3421.0 Revision(556246)

Change Log URL: 
https://chromium.googlesource.com/chromium/src/+log/77cabfa82c67864efceacaa9c3535207fb7196ea..631f3b472d49830f9e09a0eb4d0660b6970e4e7a

Unable to find any possible suspect from the above change log. Hence, marking it as untriaged and requesting some one from Services>SignIn team to please help us in assigning it to the right owner.
Note: Adding stable blocker for M-68 as it seems to be a recent regression. Please feel free to remove the same if not appropriate. 

Thanks...!!

kanterdj@gmail.com: Is this a local developer build of Chromium? If so, then you need to set API keys to sign in to Google on the web from the regular profile - please follow the instructions at https://www.chromium.org/developers/how-tos/api-keys to create and add an API key to your local build.

This is a downloaded nightly binary from the Chromium went site. I've never
had to use API keys before. Has something changed?

msarda@,
Friendly ping.

Please respond to C#13.
Thanks..!

 Issue 847142  has been merged into this issue.

As per comment #11, assigning it to msarda@ from the change log as follows:

Change Log URL: 
https://chromium.googlesource.com/chromium/src/+log/77cabfa82c67864efceacaa9c3535207fb7196ea..631f3b472d49830f9e09a0eb4d0660b6970e4e7a

From the above change log suspecting below change
Change-Id: I752bf7e9e03da0ddd33841e42ec1c550fcaf91c7
Reviewed-on: https://chromium-review.googlesource.com/1044210

msarda@ - Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.
Note: Adding stable blocker for M-68 as it seems to be a recent regression. Please feel free to remove the same if not appropriate.

Thanks...!!

kanterdj@gmail.com: [TL;DR] API keys are needed to sign in to Gmail from Chromium builds.

My CL https://chromium-review.googlesource.com/c/chromium/src/+/1044210 enabled miltestone 2 of Desktop Identity Consistency for developer builds and some bots. Starting with this CL, Chrome will retrieve a OAuth2 login scope token for all accounts when the user signs in to Google web (e.g gmail). This makes the API keys required for developer builds in order to sign in to Gmail.

I will send an email about this to chromium-dev@ (that has slipped somehow).

This should presumably be resolved "Won't Fix", right?

Correct.

 Issue 789373  has been merged into this issue.

I think we should look into this as I was wrong in comment #17 - Google web sign-in should continue to work if there are no client IDs configured.

David: Would you have time to take a look at this issue this week? If not, then please assign it to me and I will take a look next week.

kanterdj: You should still be able to sign into gmail. Is this still happening? 
If so, can you post a screenshot of chrome://signin-internals ?

I'm making the bug private to Google (Restrict-View-Google), because this webpage may contain personal information.

After taking the screenshot, can you go to chrome://flags/#account-consistency and change the value in "Identity consistency between browser and cookie jar" to "Enabled Dice (fix auth errors)", restart Chrome and check if the problem is fixed?

kanterdj@, Please update the bug as per C#23.
Thanks..!

We understand the issue now, working on a fix.

droger@ Will it be possible to mark this bug as public, as many users are reporting this issue?

Thanks..

Yes, making the bug public again.

kanterdj: we no longer need your additional information.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e

commit 4fd11d48d6c82826fe8c84aaaf81d9449d81c23e
Author: David Roger <droger@chromium.org>
Date: Wed Jun 13 15:05:29 2018

[signin] Fix account consistency value on the IO thread

The account consistency was wrong on the IO thread: it was rebuilt
from the Finch experiment config and the migration pref. However
this is not enough, and edge cases were missed, such as supervised
profiles and missing client ID.

This CL no longer rebuilds the account consistency method on the IO
thread, but instead simply passes the value from the UI thread.

Bug:  844250 
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I735005277823196a31553cc85010ca0c89eed30b
Reviewed-on: https://chromium-review.googlesource.com/1097403
Commit-Queue: David Roger <droger@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566832}
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/loader/chrome_resource_dispatcher_host_delegate_browsertest.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/profiles/profile_io_data.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/profiles/profile_io_data.h
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/signin/account_consistency_mode_manager.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/signin/account_consistency_mode_manager.h
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/signin/chrome_signin_helper.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/components/signin/core/browser/profile_management_switches.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/components/signin/core/browser/profile_management_switches.h
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/components/signin/core/browser/profile_management_switches_unittest.cc
[modify] https://crrev.com/4fd11d48d6c82826fe8c84aaaf81d9449d81c23e/testing/buildbot/filters/mojo.fyi.network_browser_tests.filter

This should be fixed now.

Note: the bug was only happening for developer builds (i.e. Chromium) with missing API keys.
Signing into a Google website (like gmail), on a non-incognito profile, now uses the API keys if they are present. There was a bug in the way we check for the presence of the API keys, and the codepath using the API keys was used even when in the absence of the keys, which caused a login error.

[Auto-generated comment by a script] We noticed that this issue is targeted for M-68; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-68 label, otherwise remove Merge-TBD label. Thanks.

droger@ do we need to merge this to M68? 

No, we don't need to merge this. It is related to developer builds, which are not using Chrome branches.

Updating labels.

 Issue 851857  has been merged into this issue.