diff --git a/sentry-python/5274/.gitignore b/sentry-python/5274/.gitignore
new file mode 100644
index 0000000..ab41eb8
--- /dev/null
+++ b/sentry-python/5274/.gitignore
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+.venv/
+__pycache__/
+*.pyc
+db.sqlite3
+*.lock
diff --git a/sentry-python/5274/README.md b/sentry-python/5274/README.md
new file mode 100644
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+++ b/sentry-python/5274/README.md
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+# Reproduction for sentry-python#5274
+
+**Issue:** https://github.com/getsentry/sentry-python/issues/5274
+
+## Description
+
+When running Django under ASGI with `send_default_pii=True`, Sentry's Django integration calls `request.user.is_authenticated` synchronously in the ASGI event processor. On Django 5.x this triggers lazy session-backed user resolution in an async context and raises `SynchronousOnlyOperation`.
+
+## Steps to Reproduce
+
+1. Install dependencies:
+   ```bash
+   uv sync
+   ```
+
+2. Set up the database and create a superuser:
+   ```bash
+   uv run python manage.py migrate
+   uv run python manage.py createsuperuser --username admin --email admin@example.com
+   ```
+
+3. (Optional) Set your Sentry DSN to see events:
+   ```bash
+   export SENTRY_DSN="your-dsn-here"
+   ```
+
+4. Run the server with uvicorn (ASGI):
+   ```bash
+   uv run uvicorn asgi:application --host 127.0.0.1 --port 8000
+   ```
+
+5. In a browser:
+   - Go to http://127.0.0.1:8000/admin/ and log in
+   - Then visit http://127.0.0.1:8000/
+
+6. Check the console output for the error.
+
+## Expected Behavior
+
+The Sentry SDK should capture errors without raising `SynchronousOnlyOperation`. In async contexts, the Django integration should use async-safe APIs (e.g., `request.auser()`) or skip user capture.
+
+## Actual Behavior
+
+Sentry logs an internal SDK error:
+
+```
+SynchronousOnlyOperation: You cannot call this from an async context - use a thread or sync_to_async.
+```
+
+The error occurs in the stack:
+```
+.../sentry_sdk/integrations/django/__init__.py in is_authenticated
+    return request_user.is_authenticated
+.../sentry_sdk/integrations/django/__init__.py in _set_user_info
+    if user is None or not is_authenticated(user):
+.../sentry_sdk/integrations/django/asgi.py in asgi_request_event_processor
+    _set_user_info(request, event)
+```
+
+## Workaround
+
+Set `send_default_pii=False` and manually call `sentry_sdk.set_user()` after resolving the user asynchronously.
+
+## Environment
+
+- Python: 3.11+
+- Django: 5.1+
+- sentry-sdk: 2.48.0+
+- ASGI server: uvicorn
diff --git a/sentry-python/5274/asgi.py b/sentry-python/5274/asgi.py
new file mode 100644
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--- /dev/null
+++ b/sentry-python/5274/asgi.py
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+import os
+from django.core.asgi import get_asgi_application
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")
+application = get_asgi_application()
diff --git a/sentry-python/5274/manage.py b/sentry-python/5274/manage.py
new file mode 100644
index 0000000..87ab2e2
--- /dev/null
+++ b/sentry-python/5274/manage.py
@@ -0,0 +1,8 @@
+#!/usr/bin/env python
+import os
+import sys
+
+if __name__ == "__main__":
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")
+    from django.core.management import execute_from_command_line
+    execute_from_command_line(sys.argv)
diff --git a/sentry-python/5274/pyproject.toml b/sentry-python/5274/pyproject.toml
new file mode 100644
index 0000000..41ed15f
--- /dev/null
+++ b/sentry-python/5274/pyproject.toml
@@ -0,0 +1,13 @@
+[project]
+name = "django-asgi-send-default-pii-repro"
+version = "0.1.0"
+description = "Reproduction for sentry-python#5274"
+requires-python = ">=3.11"
+dependencies = [
+    "django>=5.1",
+    "sentry-sdk>=2.48.0",
+    "uvicorn",
+]
+
+[tool.uv]
+dev-dependencies = []
diff --git a/sentry-python/5274/settings.py b/sentry-python/5274/settings.py
new file mode 100644
index 0000000..a589b84
--- /dev/null
+++ b/sentry-python/5274/settings.py
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+import os
+import sentry_sdk
+
+# Initialize Sentry with send_default_pii=True
+# This triggers the bug when accessing request.user in async context
+sentry_sdk.init(
+    dsn=os.environ.get("SENTRY_DSN", ""),
+    send_default_pii=True,  # <-- This causes the issue in ASGI
+    traces_sample_rate=1.0,
+)
+
+SECRET_KEY = "insecure-secret-key-for-repro"
+DEBUG = True
+ALLOWED_HOSTS = ["*"]
+
+INSTALLED_APPS = [
+    "django.contrib.admin",
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.staticfiles",
+]
+
+MIDDLEWARE = [
+    "django.middleware.security.SecurityMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+]
+
+ROOT_URLCONF = "urls"
+
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+            ],
+        },
+    },
+]
+
+ASGI_APPLICATION = "asgi.application"
+
+DATABASES = {
+    "default": {
+        "ENGINE": "django.db.backends.sqlite3",
+        "NAME": "db.sqlite3",
+    }
+}
+
+STATIC_URL = "/static/"
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"
diff --git a/sentry-python/5274/urls.py b/sentry-python/5274/urls.py
new file mode 100644
index 0000000..ac462a3
--- /dev/null
+++ b/sentry-python/5274/urls.py
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+import logging
+from django.contrib import admin
+from django.urls import path
+from django.http import HttpResponse
+
+# Enable debug logging for sentry_sdk to see internal errors
+logging.basicConfig(level=logging.DEBUG)
+logging.getLogger("sentry_sdk").setLevel(logging.DEBUG)
+
+
+async def async_view(request):
+    """
+    An async view that triggers Sentry error capture.
+
+    When send_default_pii=True, Sentry's Django integration will try to
+    access request.user.is_authenticated synchronously in the ASGI event
+    processor, which triggers SynchronousOnlyOperation on Django 5.x.
+
+    The error happens in sentry_sdk/integrations/django/asgi.py when
+    _set_user_info() is called, which accesses request.user.is_authenticated.
+    """
+    print(f"\n{'='*60}")
+    print(f"Request user type: {type(request.user)}")
+    print(f"Is async context: True (this is an async view)")
+    print(f"{'='*60}\n")
+
+    # Trigger an error to be captured by Sentry
+    # The bug manifests when Sentry tries to capture user info
+    try:
+        raise ValueError("Test error to trigger Sentry capture")
+    except ValueError:
+        import sentry_sdk
+        # This capture_exception call triggers the ASGI event processor
+        # which will try to access request.user.is_authenticated synchronously
+        sentry_sdk.capture_exception()
+        print("Exception captured by Sentry - check for SynchronousOnlyOperation in logs")
+
+    return HttpResponse(
+        "Check the server console for SynchronousOnlyOperation error from Sentry SDK.\n"
+        "The error occurs when Sentry tries to access request.user.is_authenticated "
+        "in the ASGI event processor."
+    )
+
+
+urlpatterns = [
+    path("admin/", admin.site.urls),
+    path("", async_view),
+]