We have a local portal. I created a custom widget, add it in the IIS. The manifest is visible in the browser.
When I try adding it in the portal (Content->Add item->Application-> Application Extension) after I complete the Manifest URL, the Title is automatically completed, I added a Tag and click on the Add Item. At this step a message window appear: Error: There was an error.
How can I found out the reason of the error? I looked in the https://..../portal/portaladmin, there is no error there. The server is configured to log Warnings and above.