[python] Django - Did you forget to register or load this tag?

I've created a custom tag that I want to use, but Django can't seem to find it. My templatetags directory is set up like this:

pygmentize.py

from pygments import highlight
from pygments.lexers import get_lexer_by_name
from django import template
from pygments.formatters.other import NullFormatter

register = template.Library()

@register.tag(name='code')
def do_code(parser,token):
    code = token.split_contents()[-1]
    nodelist = parser.parse(('endcode',))
    parser.delete_first_token()
    return CodeNode(code,nodelist)

class CodeNode(template.Node):
    def __init__(self,lang,code):
        self.lang = lang
        self.nodelist = code

    def render(self,context):
        code = self.nodelist.render(context)
        lexer = get_lexer_by_name('python')
        return highlight(code,lexer,NullFormatter())

I am trying to use this tag to render code in gameprofile.html.

gameprofile.html

(% load pygmentize %}
{% block content %}
    <title>{% block title %} | {{ game.title }}{% endblock %}</title>
    <div id="gamecodecontainer">
        {% code %}
            {{game.code}}
        {% endcode %}
    </div>
{% endblock content %}

When I navigate to gameprofile.html, I get an error:

Invalid block tag on line 23: 'code', expected 'endblock'. Did you forget to register or load this tag?

{% load static %}

Please add this template tag on top of the HTML or base HTML file

For Django 2.2 up to 3, you have to load staticfiles in html template first before use static keyword

{% load staticfiles %}
<link rel="stylesheet" href="{% static 'css/bootstrap.min.css' %}">

For other versions use static

{% load static %}
<link rel="stylesheet" href="{% static 'css/bootstrap.min.css' %}">

Also you have to check that you defined STATIC_URL in setting.py

At last, make sure the static files exist in the defined folder

I had the same problem, here's how I solved it. Following the first section of this very excellent Django tutorial, I did the following:

1. Create a new Django app by executing: python manage.py startapp new_app
2. Edit the settings.py file, adding the following to the list of INSTALLED_APPS: 'new_app',
3. Add a new module to the new_app package named new_app_tags.
4. In a Django HTML template, add the following to the top of the file, but after {% extends 'base_template_name.html' %}: {% load new_app_tags %}
5. In the new_app_tags module file, create a custom template tag (see below).
6. In the same Django HTML template, from step 4 above, use your shiney new custom tag like so: {% multiply_by_two | "5.0" %}
7. Celebrate!

Example from step 5 above:

from django import template

register = template.Library()

@register.simple_tag
def multiply_by_two(value):
    return float(value) * 2.0

did you try this

{% load games_tags %} 

at the top instead of pygmentize?

The error is in this line: (% load pygmentize %}, an invalid tag. Change it to {% load pygmentize %}

In gameprofile.html please change the tag {% endblock content %} to {% endblock %} then it works otherwise django will not load the endblock and give error.

You need to change:

{% endblock content %}

to

{% endblock %}

The app that contains the custom tags must be in INSTALLED_APPS. So Are you sure that your directory is in INSTALLED_APPS ?

From the documentation:

The app that contains the custom tags must be in INSTALLED_APPS in order for the {% load %} tag to work. This is a security feature: It allows you to host Python code for many template libraries on a single host machine without enabling access to all of them for every Django installation.

{% load static %}
<img src="{% static "my_app/example.jpg" %}" alt="My image">

in your templates, use the static template tag to build the URL for the given relative path using the configured STATICFILES_STORAGE.