Not compatible with bootstrap 4 -

[kamranbashir]

The dropdown does not work in bootstrap 4

[fk]

Hi @kamranbashir! I added the Bootstrap 3/Select2 v3 version of this project, located in the bootstrap3 branch, and also maintained this project for a little while. If you need an (unmaintained) Select2 v3 integration for Bootstrap 2 or 3, you are in the right place.

If you are using Select2 v4, you can find a similar integration for Bootstrap 3 at https://github.com/select2/select2-bootstrap-theme. Select2 v4 added theming capabilities, I adjusted the original select2-bootstrap-css to work with v4, and the Select2 organization officially adopted the theme.

Unfortunately, https://github.com/select2/select2-bootstrap-theme is not yet ready for Bootstrap 4, but if you are not afraid of compiling the CSS yourself, you can take a look at select2/select2-bootstrap-theme#60 where the users of the theme came up with some workarounds for Bootstrap 4.