{"record":{"id":"795de00021b3bb04","repo":"hyperledger/fabric","slug":"error-decoding-the-length-of-block-data","errorCode":null,"errorMessage":"error decoding the length of block data","messagePattern":"error decoding the length of block data","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"common/ledger/blkstorage/block_serialization.go","lineNumber":140,"sourceCode":"\t\treturn nil, errors.Wrap(err, \"error decoding the data hash\")\n\t}\n\tif header.PreviousHash, err = buf.DecodeRawBytes(false); err != nil {\n\t\treturn nil, errors.Wrap(err, \"error decoding the previous hash\")\n\t}\n\tif len(header.PreviousHash) == 0 {\n\t\theader.PreviousHash = nil\n\t}\n\treturn header, nil\n}\n\nfunc extractData(buf *buffer) (*common.BlockData, []*txindexInfo, error) {\n\tdata := &common.BlockData{}\n\tvar txOffsets []*txindexInfo\n\tvar numItems uint64\n\tvar err error\n\n\tif numItems, err = buf.DecodeVarint(); err != nil {\n\t\treturn nil, nil, errors.Wrap(err, \"error decoding the length of block data\")\n\t}\n\tfor i := uint64(0); i < numItems; i++ {\n\t\tvar txEnvBytes []byte\n\t\tvar txid string\n\t\ttxOffset := buf.GetBytesConsumed()\n\t\tif txEnvBytes, err = buf.DecodeRawBytes(false); err != nil {\n\t\t\treturn nil, nil, errors.Wrap(err, \"error decoding the transaction envelope\")\n\t\t}\n\t\tif txid, err = protoutil.GetOrComputeTxIDFromEnvelope(txEnvBytes); err != nil {\n\t\t\tlogger.Warningf(\"error while extracting txid from tx envelope bytes during deserialization of block. Ignoring this error as this is caused by a malformed transaction. Error:%s\",\n\t\t\t\terr)\n\t\t}\n\t\tdata.Data = append(data.Data, txEnvBytes)\n\t\tidxInfo := &txindexInfo{txID: txid, loc: &locPointer{txOffset, buf.GetBytesConsumed() - txOffset}}\n\t\ttxOffsets = append(txOffsets, idxInfo)\n\t}\n\treturn data, txOffsets, nil\n}","sourceCodeStart":122,"sourceCodeEnd":158,"githubUrl":"https://github.com/hyperledger/fabric/blob/2736b63f8fd5932511d56fe68b7039d15977f7f6/common/ledger/blkstorage/block_serialization.go#L122-L158","documentation":"extractData decodes the count of data items (transactions) in the block as a varint. If that length cannot be decoded, this error is thrown. The serialized block's data section is missing or the stream is desynchronized from prior corruption.","triggerScenarios":"deserializeBlock/extractSerializedBlockInfo on a block whose bytes are truncated after the header fields, before the data-length varint, or whose header decoding consumed an incorrect number of bytes due to corruption.","commonSituations":"Block file corruption after unclean shutdown; manual edits of ledger files; interrupted file copy when migrating peers.","solutions":["Restore block files from a healthy backup or obtain the missing blocks from another node.","Rebuild the ledger for the channel (remove storage, re-join the channel).","Audit storage operations: never mutate or partially write block files; use atomic file operations.","Check for disk faults and free-space issues on the ledger path."],"exampleFix":"null","handlingStrategy":"try-catch","validationCode":"if len(blockBytes) < serializedHeaderOverhead+2 {\n    return errors.New(\"block bytes too short to include data section\")\n}","typeGuard":"func isDataSectionDecodeFailure(err error) bool {\n    return err != nil && strings.Contains(err.Error(), \"error decoding the length of block data\")\n}","tryCatchPattern":"data, _, err := extractData(buf)\nif err != nil {\n    if isDataSectionDecodeFailure(err) {\n        // treat block as corrupt: resync from orderers\n    }\n    return err\n}","preventionTips":["Monitor for disk-full conditions that truncate block writes.","Restore ledgers only from complete, verified backups.","Prevent concurrent processes from writing to blkstorage directories.","Use version-compatible tooling when migrating ledger data between Fabric versions."],"tags":["hyperledger-fabric","ledger","serialization","corruption"],"backgroundTag":"ledger-block-corruption","analyzedSha":"2736b63f8fd5932511d56fe68b7039d15977f7f6","analyzedAt":"2026-09-04T08:52:36.465Z","contentChangedAt":"2026-09-04T08:52:36.465Z","schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}