Django Newbie : "Reverse not found"

Do you have a view named viewPlan with which you do something like this in a template:

{% url viewPlan %}

or something like this in a view:

reverse('viewPlan')

If you do that and you do not have a line that looks like this:

url(r'^whatever/url/$', 'dev_env.profiles.views.viewPlan', name="viewPlan"),

...in your url configuration I would imagine that's the error you're getting. Alternatively, and more likely, you are probably capturing a value (maybe id or something) in the viewPlan URL but are not passing an argument when reversing the url. So if you are capturing any values in the regex, like this:

url(r'^plans/(\d+)$', 'dev_env.profiles.views.viewPlan', name="viewPlan"),

You need to call it like this:

{% url viewPlan 15 %}

Or like this:

reverse('viewPlan', args=[15]);

Where 15 is obviously whatever the captured value is expecting.

Sometimes need to include the app_label in the name argument

like when define app_name='core' in your core.urls

then reverse the viewPlan path would be:

reverse('core:viewPlan', args=[15]);

I had the same issue. In my case, I'd forgotten to add the urls for the child app in the main urls.py file:

urlpatterns = [
    re_path("admin/", admin.site.urls),
    re_path(r"^core/", include("core.urls")),
    re_path(r"^$", welcome, name="welcome")
]