Hi @Clover J
Thank you for reaching out with your question about using Synapse Notebook references. Based on the error message you received, it seems like the notebook you are trying to reference may not be in the correct location or may not exist.
Can you please try running the %run command without the single quotes around the notebook name, like this: %run notebook_1
This should work as long as the notebook file is in the root folder of Synapse notebooks and has been published.
Hope this helps. Do let us know if you any further queries.
If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.