Account Engagement Lightning App displays "An error has occurred This page has an error. You might just need to refresh it."

The likely root cause of this issue is due to the configuration of the connected app responsible for giving user’s access to the Account Engagement Lightning which is the ‘b2bma_canvas’ connected app. It likely has been changed to ‘All users may self-authorize’ instead of ‘Admin approved users are pre-authorized’. This has to be changed do only allow specific profiles/permissions sets to access the b2bma_canvas connected app . The steps to do this would involve a Salesforce Admin doing the following:

1. In the System Administrator setup menu in Salesforce, go to the ‘Manage Connected Apps’ page.
2. Select the ‘b2bma_canvas’ connected app to go to page for this connected app.
3. Select the ‘Edit Policies’ button on the ‘b2bma_canvas’ connected app page.
4. In the OAuth Policies section, set the Permitted User’s to ‘Admin approved users are pre-authorized’ and save the change.
5. On the ‘b2bma_canvas’ connected app, scroll down to the Profiles section, select the ‘Manage Profiles’ button and add all the Salesforce profiles of the user’s who require access to the Account Engagement Lightning App. Save the change.(this step could also be done with a permission set instead of a profile)

If there is still the same error after doing these steps, your browser's privacy settings can also prevent the Account Engagement Lighting App from properly displaying data. Ensure the browser is configured to accept cookies, including third-party cookies.. Instructions for a wide variety of browsers can be found in this external resource. Account Engagement Support is unable to assist with any processes outlined therein.