diff --git a/RELEASE_1.2.1.md b/RELEASE_1.2.1.md
new file mode 100644
index 0000000..3922249
--- /dev/null
+++ b/RELEASE_1.2.1.md
@@ -0,0 +1,40 @@
+# Release 1.2.1 — async driver fallback hotfix
+
+Bugfix release for v1.2.0.
+
+## What changed
+
+### Fixed
+- **Crash at adapter init when async DB driver is missing.** Since v1.2.0 the
+  default `SQLAlchemyAdapter` was always created with an explicit
+  `async_database_url`, which caused `create_async_engine()` to raise
+  `ModuleNotFoundError: No module named 'aiosqlite'` (or `asyncpg` /
+  `aiomysql`) at construction time, breaking purely-synchronous setups.
+
+  Now the adapter degrades gracefully: if the async DB-API driver is not
+  installed, `async_engine` and `AsyncSessionLocal` fall back to `None` and
+  `get_async_session()` raises a helpful `RuntimeError` explaining which
+  package to install. Sync usage continues to work without any extra
+  dependency.
+
+### Internal
+- Switched packaging in `pyproject.toml` from a hard-coded package list to
+  `[tool.setuptools.packages.find]`, so any future subpackages are picked up
+  automatically by the wheel/sdist build.
+- Added regression tests covering both the explicit-URL and auto-converted-URL
+  paths when `aiosqlite` is missing.
+
+## Upgrade
+
+```bash
+pip install -U fastapi-viewsets==1.2.1
+```
+
+No code changes are required. If you want full async support, install the
+matching driver:
+
+```bash
+pip install aiosqlite     # SQLite
+pip install asyncpg       # PostgreSQL
+pip install aiomysql      # MySQL
+```
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index ce8c20c..10d9658 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,5 +1,21 @@
 # Release Notes
 
+## Version 1.2.1
+
+### 🐛 Bugfix
+
+- **`SQLAlchemyAdapter` no longer crashes at construction** when the
+  async DB-API driver (`aiosqlite` / `asyncpg` / `aiomysql`) is missing.
+  Sync-only setups keep working out of the box; `get_async_session()`
+  raises a helpful `RuntimeError` lazily if you try to use async without
+  the driver. Regression introduced in 1.2.0 by always passing an
+  explicit `async_database_url` from `ORMFactory.get_adapter_from_env`.
+
+### 📦 Packaging
+
+- Switched to `[tool.setuptools.packages.find]` so future subpackages are
+  picked up automatically by wheel/sdist builds.
+
 ## Version 1.2.0
 
 ### ✨ Highlights
diff --git a/fastapi_viewsets/orm/sqlalchemy_adapter.py b/fastapi_viewsets/orm/sqlalchemy_adapter.py
index efe8e6b..f211e18 100644
--- a/fastapi_viewsets/orm/sqlalchemy_adapter.py
+++ b/fastapi_viewsets/orm/sqlalchemy_adapter.py
@@ -67,19 +67,25 @@ def __init__(
         
         self.Base.query = self.db_session.query_property()
         
-        # Setup async engine and session
+        # Setup async engine and session.
+        #
+        # The async engine is best-effort: if the matching async DB-API
+        # driver (aiosqlite, asyncpg, aiomysql, ...) is not installed we
+        # fall back to ``async_engine = None`` so that purely synchronous
+        # usage still works. The error is re-raised lazily from
+        # :meth:`get_async_session` with installation hints.
         if async_engine:
             self.async_engine = async_engine
-        elif async_database_url:
-            self.async_engine = create_async_engine(async_database_url, echo=False)
         else:
-            # Auto-convert sync URL to async
-            async_url = self._get_async_database_url()
+            async_url = async_database_url or self._get_async_database_url()
             try:
                 self.async_engine = create_async_engine(async_url, echo=False)
             except Exception:
+                # Missing async DB-API driver (aiosqlite/asyncpg/aiomysql),
+                # or no async dialect for this URL — degrade to sync-only mode.
+                # The error is re-raised lazily from ``get_async_session``.
                 self.async_engine = None
-        
+
         if self.async_engine:
             self.AsyncSessionLocal = async_sessionmaker(
                 self.async_engine,
diff --git a/pyproject.toml b/pyproject.toml
index a327941..82d45e1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "fastapi_viewsets"
-version = "1.2.0"
+version = "1.2.1"
 description = "DRF-style viewsets for FastAPI with SQLAlchemy/Tortoise/Peewee adapters and Pydantic v2 support."
 readme = "README.md"
 license = { text = "MIT" }
@@ -51,8 +51,10 @@ Homepage = "https://github.com/svalench/fastapi_viewsets"
 Issues = "https://github.com/svalench/fastapi_viewsets/issues"
 Changelog = "https://github.com/svalench/fastapi_viewsets/blob/main/RELEASE_NOTES.md"
 
-[tool.setuptools]
-packages = ["fastapi_viewsets", "fastapi_viewsets.orm"]
+[tool.setuptools.packages.find]
+where = ["."]
+include = ["fastapi_viewsets*"]
+exclude = ["tests*"]
 
 [tool.black]
 line-length = 100
diff --git a/tests/test_async_driver_missing.py b/tests/test_async_driver_missing.py
new file mode 100644
index 0000000..d64eb99
--- /dev/null
+++ b/tests/test_async_driver_missing.py
@@ -0,0 +1,57 @@
+"""Regression test for v1.2.1.
+
+When ``async_database_url`` is provided but the corresponding async DB-API
+driver (e.g. ``aiosqlite``) is not installed, ``SQLAlchemyAdapter.__init__``
+must degrade gracefully to sync-only mode instead of raising
+``ModuleNotFoundError`` at construction time.
+
+Regression introduced in v1.2.0 where ``ORMFactory.get_adapter_from_env``
+started always passing an explicit ``async_database_url`` to the adapter,
+bypassing the existing best-effort ``try/except`` on the URL-conversion path.
+"""
+
+from unittest.mock import patch
+
+import pytest
+
+from fastapi_viewsets.orm.sqlalchemy_adapter import SQLAlchemyAdapter
+
+
+def _import_error(*_args, **_kwargs):
+    raise ModuleNotFoundError("No module named 'aiosqlite'")
+
+
+def test_explicit_async_url_without_driver_falls_back_to_sync():
+    """Adapter must not raise when async driver is missing."""
+    with patch(
+        "fastapi_viewsets.orm.sqlalchemy_adapter.create_async_engine",
+        side_effect=_import_error,
+    ):
+        adapter = SQLAlchemyAdapter(
+            database_url="sqlite:///:memory:",
+            async_database_url="sqlite+aiosqlite:///:memory:",
+        )
+
+    assert adapter.async_engine is None
+    assert adapter.AsyncSessionLocal is None
+
+    # Sync session must keep working.
+    session = adapter.get_session()
+    assert session is not None
+    session.close()
+
+    # Async session must raise a helpful runtime error (not at __init__).
+    with pytest.raises(RuntimeError, match="async database driver"):
+        adapter.get_async_session()
+
+
+def test_auto_converted_async_url_without_driver_falls_back_to_sync():
+    """Same fallback when ``async_database_url`` is auto-derived."""
+    with patch(
+        "fastapi_viewsets.orm.sqlalchemy_adapter.create_async_engine",
+        side_effect=_import_error,
+    ):
+        adapter = SQLAlchemyAdapter(database_url="sqlite:///:memory:")
+
+    assert adapter.async_engine is None
+    assert adapter.AsyncSessionLocal is None