[Django]-Reverse for 'plan_edit' with keyword arguments '{'pk': ''}' not found. 1 pattern(s) tried: ['palan/edit$']

You don’t have a context variable named post in your view. Change the following line

<a href="{% url 'plan_edit' pk=post.pk %}">

to

<a href="{% url 'plan_edit' pk=palan.pk %}">