Instead of

df_tag_session = load_delta_table_to_df.alias("tag_session_load_delta_table_to_df")

you need

df_tag_session = load_delta_table_to_df.alias("tag_session_load_delta_table_to_df")()

ahh crazy.. thanks so much for the quick help Nick, that did the trick, newbie error 🙂. But yes I was a bit confused by the error message. Thanks also for the ticket, not important but it (can) lead you in a complete wrong direction.