diff --git a/airflow/migrations/versions/0135_2_9_0_add_run_id_to_audit_log_table_and_change_event_name_length.py b/airflow/migrations/versions/0135_2_9_0_add_run_id_to_audit_log_table_and_change_event_name_length.py
index 44bef77578b65..22b9c4337811b 100644
--- a/airflow/migrations/versions/0135_2_9_0_add_run_id_to_audit_log_table_and_change_event_name_length.py
+++ b/airflow/migrations/versions/0135_2_9_0_add_run_id_to_audit_log_table_and_change_event_name_length.py
@@ -59,8 +59,8 @@ def downgrade():
     if conn.dialect.name == "mssql":
         with op.batch_alter_table("log") as batch_op:
             batch_op.drop_index("idx_log_event")
-            batch_op.alter_column("event", type_=sa.String(30), nullable=False)
+            batch_op.alter_column("event", type_=sa.String(30))
             batch_op.create_index("idx_log_event", ["event"])
     else:
         with op.batch_alter_table("log") as batch_op:
-            batch_op.alter_column("event", type_=sa.String(30), nullable=False)
+            batch_op.alter_column("event", type_=sa.String(30))
diff --git a/docs/apache-airflow/img/airflow_erd.sha256 b/docs/apache-airflow/img/airflow_erd.sha256
index ddee93beb4e24..69bdbd6b3fcc1 100644
--- a/docs/apache-airflow/img/airflow_erd.sha256
+++ b/docs/apache-airflow/img/airflow_erd.sha256
@@ -1 +1 @@
-c70c94b125dfd0a0e24d5815b6474e525e42a801d6b4915a3a97ca074d80b67e
\ No newline at end of file
+71cb256083f5a9ef692cd7e0320fed0764b8d664d7b9b851c3bdb804186b8022
\ No newline at end of file