The error you are encountering is because you are trying to copy data from a folder in Snowflake to a single file in Blob Storage, while preserving the folder hierarchy. This is not allowed.
You can copy the data to separate files in Blob Storage instead of a single file. You can use a wildcard (*) in the target blob name to dynamically generate the file names based on the source file names :
copy into @my_blob_stage/my_container/foldername/*.csv
If you really need to copy the data to a single file in Blob Storage, you will need to flatten the folder hierarchy by concatenating the data from all source files. This will require additional processing in Snowflake before copying the data.
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