Downgrading from bootstrap 4 to 3

I was working on a project and wanted try using bootstrap 4.0 in yii2 and added


"yiisoft/yii2-bootstrap": "~2.1.0@dev"

to my composer.json file. After a composer update bootstrap 4.0 was installed successfully but after I browsed through my site I noticed that the


yii\bootstrap\Modal

component was not functioning. Now I want to revert back to bootstrap 3 and tried changing the entry in my composer.json file to


"yiisoft/yii2-bootstrap": "~2.0.0"

but when I tried to run


composer update

I got the following error…


Your requirements could not be resolved to an installable set of packages.


  Problem 1

    - yiisoft/yii2-bootstrap 2.0.8 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.7 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.6 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.5 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.4 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.3 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.2 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.1 requires bower-asset/bootstrap 3.3.* | 3.2.* | 3.1.* -> no matching package found.

    - yiisoft/yii2-bootstrap 2.0.0 requires bower-asset/bootstrap 3.2.* | 3.1.* -> no matching package found.

    - Installation request for yiisoft/yii2-bootstrap ~2.0.0 -> satisfiable by yiisoft/yii2-bootstrap[2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.0.6, 2.0.7, 2.0.8].


Potential causes:

 - A typo in the package name

 - The package is not available in a stable-enough version according to your minimum-stability setting

   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.


Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Not sure how to proceed from here so as to revert back to my previous bootstrap version. Any suggestions are greatly appreciated.

Thanks.

Show me your composer.json