diff --git a/tests/test_utils.py b/tests/test_utils.py
index 3a19bbf38..f9f2005de 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1593,7 +1593,7 @@ def test_add_uploaded_files_to_db_other_failed_op(client: flask.testing.FlaskCli
     assert "Incorrect 'failed_op'." in errors["file1.txt"]["error"]
 
 
-def test_add_uploaded_files_to_db_file_not_found(client: flask.testing.FlaskClient, capfd):
+def test_add_uploaded_files_to_db_file_not_found(client: flask.testing.FlaskClient):
     """Test the return values of the function when file is not found on S3."""
     from botocore.exceptions import ClientError
 
@@ -1632,3 +1632,83 @@ def test_add_uploaded_files_to_db_file_not_found(client: flask.testing.FlaskClie
     assert file not in files_added
     assert files_added == []
     assert "File not found in S3" in errors["file1.txt"]["error"]
+
+
+def test_add_uploaded_files_to_db_file_already_in_db(client: flask.testing.FlaskClient):
+    """Function should return error if file is already in the database."""
+
+    # get a project and an existing file from this project
+    proj_in_db = models.Project.query.first()
+    file_in_db = proj_in_db.files[0]
+    assert file_in_db
+
+    log = {
+        file_in_db.name: {
+            "status": {"failed_op": "add_file_db"},
+            "path_remote": "path/to/file1.txt",
+            "subpath": "subpath",
+            "size_raw": 100,
+            "size_processed": 200,
+            "compressed": False,
+            "public_key": "public_key",
+            "salt": "salt",
+            "checksum": "checksum",
+        }
+    }
+
+    # Mock the S3 connector and head_object method
+    mock_s3conn = MagicMock()
+    mock_s3conn.resource.meta.client.head_object.return_value = None
+
+    # Call the function
+    with patch("dds_web.api.api_s3_connector.ApiS3Connector", return_value=mock_s3conn):
+        files_added, errors = utils.add_uploaded_files_to_db(proj_in_db, log)
+
+    assert files_added == []
+    assert file_in_db.name in errors
+    assert "File already in database." in errors[file_in_db.name]["error"]
+
+
+def test_add_uploaded_files_to_db_sql_error(client: flask.testing.FlaskClient):
+    """Test the return values of the function when sqlalchemy error occurs."""
+    import sqlalchemy.exc
+    from dds_web import db
+
+    # Prepare input data
+    proj_in_db = models.Project.query.first()
+    log = {
+        "file1.txt": {
+            "status": {"failed_op": "add_file_db"},
+            "path_remote": "path/to/file1.txt",
+            "subpath": "subpath",
+            "size_raw": 100,
+            "size_processed": 200,
+            "compressed": False,
+            "public_key": "public_key",
+            "salt": "salt",
+            "checksum": "checksum",
+        }
+    }
+
+    # mock ApiS3Connector
+    mock_s3conn = MagicMock()
+    mock_s3conn.resource.meta.client.head_object.return_value = None
+
+    # mock db.session.commit
+    db_session_commit_mock = MagicMock(
+        side_effect=sqlalchemy.exc.OperationalError("OperationalError", "test", "sqlalchemy")
+    )
+
+    # call add_uploaded_files_to_db
+    with patch("dds_web.api.api_s3_connector.ApiS3Connector", return_value=mock_s3conn):
+        with patch("dds_web.db.session.commit", db_session_commit_mock):
+            files_added, errors = utils.add_uploaded_files_to_db(proj_in_db, log)
+
+    # check that the file is not added to the database
+    file = models.File.query.filter_by(name="file1.txt").first()
+    assert not file
+
+    # check that the error is returned and files_added is empty
+    assert file not in files_added
+    assert files_added == []
+    assert "OperationalError" in errors["file1.txt"]["error"]