I create an extension with SharePoint Framework 1.7 with yo @microsoft/sharepoint by selecting the options as indicated below:

  • SharePoint 2019 onwards, including SharePoint Online.
  • Use the current folfer
  • Do you want to allow the tenatn admin ...? Yes
  • Extension
  • Application Customizer

I update the parameters in the server.json file. I create certificate and execute node with the commands: gulp trust-dev-cert AND gulp serve. The message to load the debug scripts is activated in the browser and when the browser debugging tool is executed the Placeholders Top and Bottom are not activated. When I generate the package with the .sppkg extension and upload it to the site the application catalog and I want to activate it in the SharePoint site collection, the error page with the correlation identifier is presented and upon consulting this error it indicates that the following:

Application error when access /_layouts/15/addanapp.aspx, Error=The system account can not perform this action.

1 Answer 1


Double check what version of the framework is being targeted. By default it points to 1.4.1 … we changed it internally to 1.4.0 and the extensions started working (none of them worked at all until that change!) Let us know if that helps for you.

Ralph in Chicago

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