Understanding BILUO error


I have successfully merged two datasets without any errors. The datasets were annotated by two different annotators using ner.manual.
I was trying to batch-train a model using ner.batch-train on this merged dataset using the following command:

prodigy ner.batch-train dataset en_core_web_lg --output ./tmp/model --n-iter 10 --eval-split 0.2 --dropout 0.2

We keep on encountering the following error which is really hard to interpret. Could you please help us in understanding the error:

Loaded model en_core_web_lg
Using 20% of accept/reject examples (21) for evaluation
Using 100% of remaining examples (1373) for training
Dropout: 0.2  Batch size: 4  Iterations: 10  

BEFORE      0.017             
Correct     3   
Incorrect   177
Entities    434               
Unknown     431               

#            LOSS         RIGHT        WRONG        ENTS         SKIP         ACCURACY  
 43%|███████████████████████████████████████████████████████████████████████████████████▊                                                                                                                 | 584/1373 [00:05<00:07, 101.96it/s]['O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'B-REQNUM', 'I-REQNUM', 'L-REQNUM', 'O', 'O', 'B-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'I-PLACE', 'L-PLACE', 'O', 'O', 'B-ISSUE', 'I-ISSUE', 'I-ISSUE', 'I-ISSUE', 'L-ISSUE', 'O']
['O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'B-REQNUM', 'I-REQNUM', 'L-REQNUM', 'O', 'O', 'O', 'O', 'O', 'B-PHONE', 'I-PHONE', 'I-PHONE', 'I-PHONE', 'I-PHONE', 'I-PHONE', 'I-PHONE', 'I-PHONE', 'L-PHONE', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O']
['O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O']
['O', 'O', 'O', 'U-ORG', 'O', 'O', 'O', 'U-DATE', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O', 'O']
Traceback (most recent call last):                                                                                                                                                                                                            
  File "/anaconda3/envs/venv36/lib/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/anaconda3/envs/venv36/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/anaconda3/envs/venv36/lib/python3.6/site-packages/prodigy/__main__.py", line 380, in <module>
    controller = recipe(*args, use_plac=True)
  File "cython_src/prodigy/core.pyx", line 212, in prodigy.core.recipe.recipe_decorator.recipe_proxy
  File "/anaconda3/envs/venv36/lib/python3.6/site-packages/plac_core.py", line 328, in call
    cmd, result = parser.consume(arglist)
  File "/anaconda3/envs/venv36/lib/python3.6/site-packages/plac_core.py", line 207, in consume
    return cmd, self.func(*(args + varargs + extraopts), **kwargs)
  File "/anaconda3/envs/venv36/lib/python3.6/site-packages/prodigy/recipes/ner.py", line 621, in batch_train
    examples, batch_size=batch_size, drop=dropout, beam_width=beam_width
  File "cython_src/prodigy/models/ner.pyx", line 362, in prodigy.models.ner.EntityRecognizer.batch_train
  File "cython_src/prodigy/models/ner.pyx", line 453, in prodigy.models.ner.EntityRecognizer._update
  File "cython_src/prodigy/models/ner.pyx", line 446, in prodigy.models.ner.EntityRecognizer._update
  File "cython_src/prodigy/models/ner.pyx", line 447, in prodigy.models.ner.EntityRecognizer._update
  File "/anaconda3/envs/venv36/lib/python3.6/site-packages/spacy/language.py", line 457, in update
    proc.update(docs, golds, sgd=get_grads, losses=losses, **kwargs)
  File "nn_parser.pyx", line 413, in spacy.syntax.nn_parser.Parser.update
  File "nn_parser.pyx", line 519, in spacy.syntax.nn_parser.Parser._init_gold_batch
  File "transition_system.pyx", line 86, in spacy.syntax.transition_system.TransitionSystem.get_oracle_sequence
  File "transition_system.pyx", line 148, in spacy.syntax.transition_system.TransitionSystem.set_costs
ValueError: [E024] Could not find an optimal move to supervise the parser. Usually, this means the GoldParse was not correct. For example, are all labels added to the model?

We are able to train the model on one dataset, export it and retrain the exported model on the second dataset, but the problem arises when we try to train on merged dataset.

Also could you please help us understand what the numbers 584/1373 mean in the following progress bar?
(Because if we count the total number annotations in the merged dataset, there are more than 1373 annotations, assuming 1373 is the number of annotations)

43%|███████████████████████████████████████████████████████████████████████████████████▊                                                                                                                 | 584/1373


Hi! It's likely that this is related to the update to spaCy v2.1, which is stricter about gold standard data and constraints for the parser and named entity recognizer. See my reply from this thread:

So you might want to double-check the data and see if you have any "illegal" spans in there. It's usually pretty rare and removing them should be no problem, because in most cases, they'd be rejected suggestions anyway.

This should be the total number of examples used for annotation after the examples were merged before training and all spans on the same input text were combined.