Please specify in your code checkpointLocation. If you have specified already please delete files which are there.

Display functions also have checkpoint and it is better not to use display in production.

For developer purposes here is whole code for streaming display function (it is good to add interval too for developing/debugging so display will be updated less frequently):

display(streaming_df, processingTime = "5 seconds", checkpointLocation = "dbfs:/<checkpoint-path>")