Last improvement. It's working now.

config/settings.py

@@ -137,6 +137,7 @@ STATIC_ROOT = BASE_DIR / 'staticfiles'
 
 
 # Media root/url
+# https://devcenter.heroku.com/articles/s3
 MEDIA_URL = "/media/"
 MEDIA_ROOT = os.path.join(BASE_DIR, "media")
 

config/urls.py

@@ -15,7 +15,9 @@ Including another URLconf
 """
 from django.contrib import admin
 from django.urls import include, path
+from django.conf.urls.static import static
 
+from config import settings
 import config.views
 import ultron.followup.urls
 import ultron.location.urls
@@ -62,4 +64,4 @@ urlpatterns = [
 
     # Administration
     path('admin/', admin.site.urls),
-]
+] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

templates/peoples/gymnasts/details.html

@@ -14,7 +14,7 @@
                         <div class="block block-four"></div>
                         <a href="javascript:void(0)">
                             {% if gymnast.picture %}
-                                <img src="{{ gymnast.picture.url }}" alt="{{ gymnast }}" class="avatar">
+                                <img src="{{ MEDIA_ROOT }}{{ gymnast.picture.url }}" alt="{{ gymnast }}" class="avatar">
                             {% endif %}
                             <h4 class="title mb-2">{{ gymnast.first_name }} {{ gymnast.last_name }}</h4>
                         </a>

ultron/people/migrations/0005_alter_gymnast_picture.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.8 on 2021-12-22 08:35
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('people', '0004_alter_gymnast_picture'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='gymnast',
+            name='picture',
+            field=models.ImageField(blank=True, null=True, upload_to='gymnast'),
+        ),
+    ]

ultron/people/views.py

@@ -343,10 +343,8 @@ def gymnast_create_or_update(request, gymnast_id=None):
 
     if request.method == "POST":
         gymnast_form = GymnastForm(request.POST, request.FILES, instance=gymnast)
-        print(gymnast_form)
 
-        if gymnast_form.is_valid(): 
-            # handle_uploaded_file(request.FILES['file'])
+        if gymnast_form.is_valid():
             gymnast = gymnast_form.save()
             return HttpResponseRedirect("/gymnast/details/" + str(gymnast.id))
         else: