You have to wait sometimes hours for the uploaded JSONL files to be ready before they are available for the “create fine-tuning” API call.
After you upload the file, it may take some time to process. While the file is processing, you can still create a fine-tuning job but it will not start until the file processing has completed.
The file object can return “status” and “status-details” when you use the storage API option to list files, but this return is deprecated since they now made fine-tuning wait instead of fail.