I have built a webpart. During the question "Which baseline packages do you want to target for your component(s)?" I picked SP Online only mistakenly.

After I completed development and upload to APP Catalog, the App for SharePoint page show error "There were errors when validating the App manifest.: Xml Validation Exception: 'The 'IsDomainIsolated' attribute is not declared.' on line '1', position '283'".

I want to convert it to SP2019 use. Is there any procedure available for reference? I don't want to re-build everything from scratch.

1 Answer 1


There's no easy path to downgrading your version. While there are definitely settings and features only available in later versions of SPFx, the bulk of your code will probably transfer fine.

I suggest using the generator to generate a new 1.4 solution (2019) then moving your code into it manually. You'll likely need to troubleshoot a few issues here and there especially around imports.

  • 1
    I would second this as - although tedious - probably the most straight-forward way to downgrade. Sep 11, 2020 at 14:53

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