Hi Martin
I just deleted the complet folder, still the same:

Ultralytics YOLOv8.0.225 🚀 Python-3.10.11 torch-2.2.0.dev20231207+cu118 CUDA:0 (NVIDIA GeForce GTX 1650 Ti with Max-Q Design, 4096MiB)
engine\trainer: task=detect, mode=train, model=yolov8n.pt, data=C:/Users/junke/.clearml/cache/storage_manager/datasets/ds_30892c41582b4537bb9508f3c09ae9ed, epochs=80, patience=50, batch=16, imgsz=640, save=True, save_period=-1, cache=False, device=0, workers=8, project=None, name=train17, exist_ok=False, pretrained=True, optimizer=auto, verbose=True, seed=0, deterministic=True, single_cls=False, rect=False, cos_lr=False, close_mosaic=10, resume=False, amp=True, fraction=1.0, profile=False, freeze=None, overlap_mask=True, mask_ratio=4, dropout=0.0, val=True, split=val, save_json=False, save_hybrid=False, conf=None, iou=0.7, max_det=300, half=False, dnn=False, plots=True, source=None, vid_stride=1, stream_buffer=False, visualize=False, augment=False, agnostic_nms=False, classes=None, retina_masks=False, show=False, save_frames=False, save_txt=False, save_conf=False, save_crop=False, show_labels=True, show_conf=True, show_boxes=True, line_width=None, format=torchscript, keras=False, optimize=False, int8=False, dynamic=False, simplify=False, opset=None, workspace=4, nms=False, lr0=0.01, lrf=0.01, momentum=0.937, weight_decay=0.0005, warmup_epochs=3.0, warmup_momentum=0.8, warmup_bias_lr=0.1, box=7.5, cls=0.5, dfl=1.5, pose=12.0, kobj=1.0, label_smoothing=0.0, nbs=64, hsv_h=0.015, hsv_s=0.7, hsv_v=0.4, degrees=0.0, translate=0.1, scale=0.5, shear=0.0, perspective=0.0, flipud=0.0, fliplr=0.5, mosaic=1.0, mixup=0.0, copy_paste=0.0, cfg=None, tracker=botsort.yaml, save_dir=runs\detect\train17
Traceback (most recent call last):
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\venv\lib\site-packages\ultralytics\engine\trainer.py", line 116, in __init__
    self.data = check_det_dataset(self.args.data)
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\venv\lib\site-packages\ultralytics\data\utils.py", line 257, in check_det_dataset
    if zipfile.is_zipfile(file) or is_tarfile(file):
  File "C:\Users\junke\AppData\Local\Programs\Python\Python310\lib\tarfile.py", line 2517, in is_tarfile
    t = open(name)
  File "C:\Users\junke\AppData\Local\Programs\Python\Python310\lib\tarfile.py", line 1632, in open
    return func(name, "r", fileobj, **kwargs)
  File "C:\Users\junke\AppData\Local\Programs\Python\Python310\lib\tarfile.py", line 1698, in gzopen
    fileobj = GzipFile(name, mode + "b", compresslevel, fileobj)
  File "C:\Users\junke\AppData\Local\Programs\Python\Python310\lib\gzip.py", line 174, in __init__
    fileobj = self.myfileobj = builtins.open(filename, mode or 'rb')
PermissionError: [Errno 13] Permission denied: 'C:/Users/junke/.clearml/cache/storage_manager/datasets/ds_30892c41582b4537bb9508f3c09ae9ed'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\training.py", line 38, in <module>
    main()
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\training.py", line 26, in main
    results = model.train(data=data,
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\venv\lib\site-packages\ultralytics\engine\model.py", line 333, in train
    self.trainer = (trainer or self._smart_load('trainer'))(overrides=args, _callbacks=self.callbacks)
  File "C:\Users\junke\Dropbox\MIR\Ausbildung\MAS Automation Management\001_Module\005_Masterarbeit\Software\003_Test_Laptop_Yoga\venv\lib\site-packages\ultralytics\engine\trainer.py", line 120, in __init__
    raise RuntimeError(emojis(f"Dataset '{clean_url(self.args.data)}' error ❌ {e}")) from e
RuntimeError: Dataset '

' error  [Errno 13] Permission denied: 'C:/Users/junke/.clearml/cache/storage_manager/datasets/ds_30892c41582b4537bb9508f3c09ae9ed'

Process finished with exit code 1