Bower is deprecating their registry hosted with Heroku. http://bower.herokuapp.com/ Will not be accessible anymore or it might be down intermittently, therefore, forcing users to a new registry.
Users working on old bower versions can update the .bowerrc file with the following data.
{
"registry": "https://registry.bower.io"
}
.bowerrc file can be located at the same folder where bower.json and bower_components folder is located. If it is not present already, you can make one.
For references check the below links