Unable to load custom widgets in ArcGIS Dashboards

Description

When transitioning to ArcGIS Dashboards, custom widgets created in ArcGIS Dashboards Classic do not function as expected. The widgets load indefinitely when viewed in ArcGIS Dashboards, and the following error returns:

Error:
Data source error

Cause

Widgets created for ArcGIS Dashboards Classic uses ArcGIS API for JavaScript version 3.x or lower. ArcGIS Dashboards only supports ArcGIS API for JavaScript version 4.x. This causes compatibility issues for widgets created in ArcGIS Dashboards Classic with ArcGIS Dashboards and vice versa.

Solution or Workaround

ArcGIS API for JavaScript 4.x is a major overhaul of ArcGIS API for JavaScript and it is recommended to rewrite the codes used in the development of widgets using the latest version of ArcGIS API for JavaScript. Refer to ArcGIS API for JavaScript: Migrating from 3.x to 4.19 for instructions on migrating applications to the latest version of ArcGIS API for JavaScript.