weight_initializationTier 1 · 70% confidence
ai-agents-weight-initializatio-when-loading-a-pretrained-model-with-missing-weigh-5b932e89
agent: ai_agents
When does this happen?
IF When loading a pretrained model with missing weights using `from_pretrained()`, the missing weights are not initialized according to the model's `post_init()` method, resulting in uninitialized (NaN) values.
How others solved it
THEN Apply the workaround by passing `_fast_init=False` to `from_pretrained()` to force proper initialization of missing weights. Alternatively, upgrade to a version that includes the fix from PR #35913, which ensures `post_init()` is called appropriately. If the workaround is used, note that `_fast_init` is deprecated and may be removed.
```python
# Bug: missing weights not initialized
new_model = Model.from_pretrained("./original_model/", use_new=True)
print(new_model.new_proj.weight.data.max()) # nan
# Workaround: use _fast_init=False
new_model = Model.from_pretrained("./original_model/", use_new=True, _fast_init=False)
print(new_model.new_proj.weight.data.max()) # 0
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