My (same) problem arose when I mixed up the css and the bootstrap versions. I have an autocomplete on my page that is bound to a sqldatasource. You can add dropdown menus to a link inside tabs and pills nav with a little extra markup. In this article, well look at how to manipulate navs with JavaScript with Bootstrap 5. Very first, you need to run below commands to set Bootstrap 4.5 behaviour into your angular 9 application: npm install --save bootstrap. I have to double-click to show the content of next tab. If you've loaded or overwrote a bunch of css and js files to your static folder recently, it would be a good place to start. I was using version 3 bootstrap.min.js with version 4.5 bootstrap.min.css. 1. The following are the classes that can be used to create and style buttons in bootstrap. Note: creating a vertical nav (.flex-column) with tabs styling is unsupported by Bootstrap's default stylesheet. Bootstrap Sam Norton April 16, 2021 14 minutes READ . Use the Bootstrap .tab (show) method to display the tabs. Navigation can also be created using