SharePoint online add a notification message in top banner of the site

[hemanthrhk]

I want to display a alert message to users at the top of the site before site migration in SP online. In SP 2016 i have implemented using powershell usercustom actions that is working fine and i did the same in online, but here it is not working. Below attached the working version of SP 2016 image. Please suggest any solutions or approach.

[#2]

Hi @hemanthrhk ,

There are many community samples that do this :)
https://github.com/pnp/sp-dev-fx-extensions/tree/master/samples/react-application-announcements

https://github.com/pnp/sp-dev-fx-extensions/tree/master/samples/react-application-alerts

https://github.com/pnp/sp-dev-fx-extensions/tree/master/samples/react-app-announcements

https://github.com/pnp/sp-dev-fx-extensions/tree/master/samples/js-application-alert-message

https://github.com/pnp/sp-dev-fx-extensions/tree/master/samples/jquery-application-toastr

Also, if you have a question specific to one of the samples above, it's probably better to ask it within the GitHub repository Issues list. That way you may get a quicker and more relevant answer

Hope this helps