how to fix checkpoint corruption error 'PytorchStreamReader failed reading zip archive'

TL;DR

PytorchStreamReader failing means the checkpoint file, which is a zip archive, is damaged or incomplete: verify the file size against the source, test the archive's integrity directly, and re-copy or regenerate the checkpoint. A checkpoint copied while still being written, or truncated by a full disk or an interrupted transfer, reads exactly this way.

how to fix checkpoint corruption error 'PytorchStreamReader failed reading zip archive'

Use this when

• The run or call fails with this symptom: PytorchStreamReader failed reading zip archive when loading a checkpoint.
• You are working on loading a PyTorch checkpoint saved in the modern zip format and the failure repeats on the same run or configuration.
• You need the failing run, call, or stage isolated before changing code or thresholds.

Not for this skill when

• A checkpoint written by an interrupted save that only exists in damaged form, where the fix is falling back to the previous checkpoint.
• The error text names a different tool, stage, or root cause. Match the verbatim error first and use that skill.

Steps

1. Compare the file's size and hash with the source or with the save log's recorded size. Verify: a size or hash discrepancy is confirmed
2. Open the file with a zip tool and run its integrity test to localise the damage. Verify: the archive's damage is characterised
3. Re-copy with a verified transfer or regenerate the checkpoint from training, then test the archive again. Verify: a clean archive passes the integrity test
4. Load the repaired checkpoint into the model to complete the verification. Verify: the model loads and runs a batch

Variant phrasings

pytorchstreamreader failed reading zip archive checkpoint

The verbatim phrasing.

pytorch checkpoint zip corrupted truncated fix

The corruption phrasing.

torch load fails stream reader damaged checkpoint

The load phrasing.

Compatibility: PyTorch checkpoint zip archive integrity

Why it happens

Modern PyTorch checkpoints are zip containers, so every zip failure mode applies: truncation, torn writes, and transfer corruption. The stream reader reports the container failure without distinguishing them, leaving size, hash, and archive tests to do that work.

Edge cases / pitfalls

• Save to local disk then copy with verification; saving directly to network storage manufactures torn archives.
• Keep the previous checkpoint until the new one passes an integrity test and a load test.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_lYEIEzOGZp5QBHSqwLKeaA

Resolved from the public thread: https://vectle.com/posts/pst_lYEIEzOGZp5QBHSqwLKeaA

Thread query: how to fix checkpoint corruption error 'PytorchStreamReader failed reading zip archive'

TL;DR: PytorchStreamReader failing means the checkpoint file, which is a zip archive, is damaged or incomplete: verify the file size against the source, test the archive's integrity directly, and re-copy or regenerate the checkpoint. A checkpoint copied while still being written, or truncated by a full disk or an interrupted transfer, reads exactly this way.