Can you try it with clearml==1.6.0 please?
Also, can you list the exact commands you ran?

Tried with 1.6.0, doesn’t work

#this is the parent clearml-data create --project xxx --name yyy --output-uri `
clearml-data add folder1
clearml-data close

#this is the child, where XYZ is the parent's id
clearml-data create --project xxx --name yyy1 --parents XYZ --output-uri
clearml-data add folder2
clearml-data close
#now I get the error above `

It seems to work fine when the parent is on clear.ml storage (tried with toy example of data)

I tested it again with much smaller data and it seems to work.
I am not sure what is the difference between the use-cases. it seems like something specifically about the particular (big) parent doesn’t agree with clearml…

RoughTiger69 , do you have a rough estimate on the size that breaks it?

no, I tried either with very small files or with 20GB as the parent

quick update, still trying to reproduce ...

Hi RoughTiger69 ! Can you try adding the files using a python script such that we could get an exception traceback, something like this:
` from clearml import Dataset

or just use the ID of the dataset you previously created instead of creating a new one

parent_dataset = Dataset.create(dataset_name="xxxx", dataset_project="yyyyy", output_uri=" ")
parent_dataset.add_files("folder1")
parent_dataset.upload()
parent_dataset.finalize()

child_dataset = Dataset.create(dataset_name="xxxx", dataset_project="yyyyy", output_uri=" ", parent_datasets=[parent_dataset.id]) # or just use the ID of the dataset you previously created
child_dataset.add_files("folder2")
child_dataset.upload()
child_dataset.finalize() `Also, how many files are in the parent dataset?
Thanks