I do have the following message in the console:
jquery upgraded from 1.9.1 to 1.11.9
This may happen when you have other npm packages with jQuery dependency defined as
In that case, if no other package defines a more strict version, npm will automatically take the most recent version that complies with this dependency specification, i.e. jQuery 3+ in that case.
If you are in that situation, a simple workaround is to add a more strict version specification in your
package.json file, e.g.
"jquery": ">=1.9.1 <3.0.0"