The new Blueprint-based assets breaks when two Dash apps try to use the same Flask instance

[ned2]

This was reported on the community forums.

import flask
import dash
import dash_html_components as html

server = flask.Flask(__name__)

app1 = dash.Dash(server=server, url_base_pathname='/app1/')
app1.layout = html.Div('app1')

app2 = dash.Dash(server=server, url_base_pathname='/app2/')
app2.layout = html.Div('app2')

if __name__ == '__main__':
    server.run()

The above example yields this error:

AssertionError: A name collision occurred between blueprints <flask.blueprints.Blueprint object at 0x7f945444ce80> and <flask.blueprints.Blueprint object at 0x7f943caa8278>. Both share the same name "assets". Blueprints that are created on the fly need unique names.