Value Error (Python)
Python value errors crash training when functions receive values of correct type but inappropriate value.
Python value errors crash training when functions receive values of correct type but inappropriate value.
What this failure is
Value Error (Python) is a Environment failure seen during ML training runs. Python value errors crash training when functions receive values of correct type but inappropriate value. Common tags: Value Error, Python, Validation, Debugging.
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Why it happens (the mechanism)
Invalid configuration value. Data validation failure. Shape mismatch in array operations. Incorrect argument value. Taken together, these mechanisms explain why the failure is reproducible, why it tends to surface on specific workloads or scales, and why generic mitigation attempts often fall short without addressing the underlying cause.
What you'll observe
- Training crashes with ValueError
- Error indicates invalid value
- Code worked in older version
Common symptoms and what they mean
| Symptom | Why it happens |
|---|---|
| ValueError: invalid value | Invalid configuration value |
| ValueError: setting array element with sequence | Data validation failure |
| ValueError: too many values to unpack | Shape mismatch in array operations |
Which systems are affected
- Custom training code
- Configuration errors
- Data validation errors
- API changes
How to confirm this is the problem
Use this checklist to test the hypothesis against a small reproduction. No single line proves the root cause, so preserve the preceding events and compare one variable at a time.
- ✓Reproduce the failure from a clean checkpoint/seed: the symptom must appear without warm-up state from a previous run.
- ✓Verified signal present: ValueError: invalid value
- ✓Verified signal present: ValueError: setting array element with sequence
- ✓Verified signal present: ValueError: too many values to unpack
- ✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.
The fix and the prevention pattern
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Diagnose this failure in VS Code
Select the traceback or open the failed terminal, then run Denpex locally to see the initiating rank, collateral failures, exact fix, and verification command without uploading the log.
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Root cause
- Invalid configuration value
- Data validation failure
- Shape mismatch in array operations
- Incorrect argument value
The fix and how to prevent it
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References
Don't just read the fix, diagnose your run
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