When you use:

from pyspark import SparkFiles
spark.sparkContext.addFile(url)

it adds file to NON dbfs /local_disk0/ but then when you want to read file:

spark.read.json(SparkFiles.get("file_name"))

it wants to read it from /dbfs/local_disk0/. I tried also with file:// and many other creative ways and it doesn't work.

Of course it is working after using %sh cp - moving from /local_disk0/ to /dbfs/local_disk0/ .

It seems to be a bug like addFile was switched to dbfs on azure databricks but SparkFiles not (in original spark it addFile and gets to/from workers).

I couldn't find also any settings to manually specify RootDirectory for SparkFiles.