A corrupted chain state occurs if a node’s local copy of the blockchain or its indexing data gets tampered with—due to hardware failures, software bugs, or malicious interference. Symptoms include failing to validate blocks or mismatched UTXO sets.

The standard fix is to re-index (rebuild the database from the raw block files) or, in severe cases, delete all local data and sync from scratch. Running a node on reliable hardware, keeping software updated, and verifying checksums can reduce the risk of chain state corruption. In a well-run setup, the blockchain’s integrity is protected by cryptographic proofs, so corruption is typically local, not network-wide.