Could you please attach the page source content to this ticket? If you are concerned that may pose a security risk for your organization, you can e-mail it to me here:

cmeyers@cloudbees.com

or we can discuss a more secure mechanism in that e-mail thread.

cliffmeyers Sent via email.

Examining the page source content, I've noticed that the following preloader entries are missing:

// State Preloader: io.jenkins.blueocean.config.BlueOceanConfigStatePreloader
setState('config', { ... });
// State Preloader: io.jenkins.blueocean.config.JenkinsJSExtensionsStatePreloader
setState('jsExtensions', [ ... ]);

barnett2 I checked your plugin list and it appears that the "Config API for Blue Ocean" (aka "io.jenkins.blueocean.blueocean-config") is missing from the list. If it were not installed, it would explain the absence of this important data. Could you check to see if it's installed and if not, try adding it?

cliffmeyers I'm pretty sure it was there previously, but is not there now [after remove / restart above?]. I've added it, and now the error is different. I did not restart Jenkins as the plugin page did not dictate it was required.

First error:
/blue/rest/i18n/blueocean-web/1.1.2/jenkins.plugins.blueocean.web.Messages/en-US Failed to load resource: the server responded with a status of 404 (Not Found)

Second error:
blueocean.js:2439 Uncaught (in promise) Error: Not Found
at checkStatus (blueocean.js:2439)
at <anonymous>

Perhaps you could post the list of "Blue Ocean" plugins installed in your instance? I'm concerned that if one was missing previously that the full list may not be correct or you may have incompatible versions of other plugins. In particular check that "Web for Blue Ocean" is version 1.1.2 and not an older version.

cliffmeyers Please see below. I noticed a little bit ago that "Blue Ocean" isn't among the installed list. Perhaps removed during the remove / restart ... I have not added it, yet. Will wait for your feedback.

Below are 2 lists showing those installed and available which match "Blue Ocean".

Current list of installed plugins:
bouncycastle API Plugin
This plugin provides an stable API to Bouncy Castle related tasks.
2.16.1
Downgrade to 2.16.0
Uninstall

Branch API Plugin
This plugin provides an API for multiple branch based projects.
2.0.10
Downgrade to 2.0.8
Uninstall

Common API for Blue Ocean
This plugin is a part of Blue Ocean UI
1.1.2
Downgrade to 1.1.1
Uninstall

Config API for Blue Ocean
BlueOcean Analytics Tools plugin
1.1.2
Uninstall

Credentials Plugin
This plugin allows you to store credentials in Jenkins.
2.1.14
Downgrade to 2.1.13
Uninstall

Dashboard for Blue Ocean
Blue Ocean Dashboard
1.1.2
Downgrade to 1.1.1
Uninstall

Events API for Blue Ocean
Blue Ocean Events
1.1.2
Downgrade to 1.1.1
Uninstall

Favorite
This plugin allows users to favorite a job.
2.3.0
Uninstall

Folders Plugin
This plugin allows users to create "folders" to organize jobs. Users can define custom taxonomies (like by project type, organization type etc). Folders are nestable and you can define views within folders. Maintained by CloudBees, Inc.
6.0.4
Downgrade to 6.0.3
Uninstall

Git plugin
This plugin integrates Git with Jenkins.
3.3.0
Downgrade to 3.1.0
Uninstall

GitHub Branch Source Plugin
Multibranch projects and organization folders from GitHub. Maintained by CloudBees, Inc.
2.0.6
Uninstall

JUnit Plugin
Allows JUnit-format test results to be published.
1.20
Downgrade to 1.19
Uninstall

JWT for Blue Ocean
BlueOcean JWT plugin: Enables JWT based BlueOcean API authentication
1.1.2
Downgrade to 1.1.1
Uninstall

Mailer Plugin
This plugin allows you to configure email notifications for build results
1.20
Downgrade to 1.19
Uninstall

Metrics Plugin
This plugin exposes the Metrics API to Jenkins plugins.
3.1.2.10
Uninstall

Pipeline Graph Analysis Plugin
Provides a REST API to access pipeline and pipeline run data.
1.4
Downgrade to 1.3
Uninstall

Pipeline implementation for Blue Ocean
This plugin is a part of BlueOcean Plugin
1.1.2
Downgrade to 1.1.1
Uninstall

Pipeline SCM API for Blue Ocean
This plugin is a part of BlueOcean Plugin
1.1.2
Downgrade to 1.1.1
Uninstall

Pipeline: API
Plugin that defines Pipeline API.
2.17
Downgrade to 2.13
Uninstall

Pipeline: Groovy
Pipeline execution engine based on continuation passing style transformation of Groovy scripts.
2.36
Downgrade to 2.35
Uninstall

Pipeline: Input Step
Adds the Pipeline step input to wait for human input or approval.
2.7
Downgrade to 2.5
Uninstall

Pipeline: Job
Defines a new job type for pipelines and provides their generic user interface.
2.11
Downgrade to 2.10
Uninstall

Pipeline: Model Definition
An opinionated, declarative Pipeline.
1.1.6
Downgrade to 1.1.3
Uninstall

Pipeline: Multibranch
Enhances Pipeline plugin to handle branches better by automatically grouping builds from different branches.
2.15
Downgrade to 2.14
Uninstall

Pipeline: Nodes and Processes
Pipeline steps locking agents and workspaces, and running external processes that may survive a Jenkins restart or slave reconnection.
2.12
Downgrade to 2.11
Uninstall

Pipeline: Stage Step
Adds the Pipeline step stage to delineate portions of a build.
2.2
Uninstall

Pipeline: Step API
API for asynchronous build step primitive.
2.11
Downgrade to 2.9
Uninstall

Pipeline: Supporting APIs
Common utility implementations to build Pipeline Plugin
2.14
Downgrade to 2.13
Uninstall

Pub-Sub "light" Bus
A simple Publish-Subscribe light-weight event bus for Jenkins
1.8
Uninstall

REST API for Blue Ocean
This plugin is a part of Blue Ocean UI
1.1.2
Downgrade to 1.1.1
Uninstall

REST Implementation for Blue Ocean
This plugin is a part of Blue Ocean UI
1.1.2
Downgrade to 1.1.1
Uninstall

SCM API Plugin
This plugin provides a new enhanced API for interacting with SCM systems.
2.1.1
Downgrade to 2.1.0
Uninstall

Server Sent Events (SSE) Gateway Plugin
Server Sent Events (SSE) Gateway.
1.15
Uninstall

Variant Plugin
This user-invisible library plugin allows other multi-modal plugins to behave differently depending on where they run.
1.1
Uninstall

Web for Blue Ocean
Blue Ocean core
1.1.2
Downgrade to 1.1.1
Uninstall

"Available" plugins matching "Blue Ocean" :

Blue Ocean
Blue Ocean is a new project that rethinks the user experience of Jenkins. Designed from the ground up for Jenkins Pipeline and compatible with Freestyle jobs, Blue Ocean reduces clutter and increases clarity for every member of your team.
1.1.2

Git Pipeline for Blue Ocean
1.1.2

GitHub Pipeline for Blue Ocean
1.1.2

i18n for Blue Ocean
1.1.2

Personalization for Blue Ocean
1.1.2

Blue Ocean Pipeline Editor
The Blue Ocean Pipeline Editor is the simplest way for anyone wanting to get started with creating Pipelines in Jenkins
0.2.0

Autofavorite for Blue Ocean
Automatically favorites multibranch pipeline jobs when user is the author
1.0.0

Yes, please install "Blue Ocean" as it should pull in all the other plugin dependencies required for proper operation. After install / restart you should see the "available plugins matching blue ocean list" slim down considerably if not entirely.

cliffmeyers Thanks. I don't know which part of this solved the issue, but one [or more] of the following have resolved the problem and all errors are now gone:

1. Stop Jenkins, remove plugins/blueocean*, Start Jenkins, install some of the Blue Ocean components – apparently, I missed some.
2. Restart Jenkins.
3. Install the "Config API for Blue Ocean"
4. Install the "Blue Ocean" plugin – apparently missed during a prior step
5. Restart Jenkins

One thing I note is that the [Blue Ocean] link across the top of the Jenkins header is removed and is replaced by a "Open Blue Ocean" link in the left-hand navigation pane.

Not 100% sure which of the above steps solved the issue, but Blue Ocean is now working.

Thank you.

Glad that it's working! The "Open Blue Ocean" link was moved to the left navigation (in 1.1, IIRC) based on some user feedback.

From the issues you were facing, it sounds like the following problems occurred:
1. "Config API for Blue Ocean" was removed at some point, which led to the "Must call ExtensionStore.init() " error
2. "Web for Blue Ocean" was using an older incompatible version, which led to the 404 for the blueocean-web@1.1.2 I18N bundle.

Please let us know if you have any further issues.

yes plugins that bring in other dependencies can be tricky when you switch between beta versions, or want to remove (it is never easy). I suspected it may be this issue. 

If you install the "Blue Ocean plugin" from the UC it will bring in the correct dependencies.