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Error means there was either no registration of the application (see also last Section of of SharePoint: Deploy Add-in package to the App Catalog (v 1.01) requiring to register the app with the correct Client ID, Confluence host and provider url), communication failed with the app web. Reasons for the later can be:
- Missing DNS entry for app web host name pointing to the SharePoint farm - see DNS part of Preparing the SharePoint Add-in Infrastructure (v 1.01)
- Certificate not accepted by browser, e.g. missing in the certificate of the SharePoint farm - see HTTPS part of of Preparing the SharePoint Add-in Infrastructure (v 1.01)
Checking assets library and loader file
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