I think, the code-based sandbox solutions are no longer going to work in SP 2019. It's one of the most promitent things removed in the latest sever version of the product: After careful consideration, we've decided to also remove support for code-based sandbox solutions in SharePoint Server 2019. Customers are recommended to explore SharePoint add-ins as an ...


I agree with Denis, as mentioned this feature has already been removed in SP 2019.


Try this <script src="../../jslib/jquery351/jquery351.min.js"></script>

Only top voted, non community-wiki answers of a minimum length are eligible