{"record":{"id":"a69a7d9c8ee94fa4","repo":"hyperledger/fabric","slug":"internal-leveldb-error-while-obtaining-db-iterator","errorCode":null,"errorMessage":"internal leveldb error while obtaining db iterator","messagePattern":"internal leveldb error while obtaining db iterator","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"common/ledger/util/leveldbhelper/leveldb_provider.go","lineNumber":300,"sourceCode":"\t}\n\treturn nil\n}\n\n// GetIterator gets an handle to iterator. The iterator should be released after the use.\n// The resultset contains all the keys that are present in the db between the startKey (inclusive) and the endKey (exclusive).\n// A nil startKey represents the first available key and a nil endKey represent a logical key after the last available key\nfunc (h *DBHandle) GetIterator(startKey []byte, endKey []byte) (*Iterator, error) {\n\tsKey := constructLevelKey(h.dbName, startKey)\n\teKey := constructLevelKey(h.dbName, endKey)\n\tif endKey == nil {\n\t\t// replace the last byte 'dbNameKeySep' by 'lastKeyIndicator'\n\t\teKey[len(eKey)-1] = lastKeyIndicator\n\t}\n\tlogger.Debugf(\"Getting iterator for range [%#v] - [%#v]\", sKey, eKey)\n\titr := h.db.GetIterator(sKey, eKey)\n\tif err := itr.Error(); err != nil {\n\t\titr.Release()\n\t\treturn nil, errors.Wrapf(err, \"internal leveldb error while obtaining db iterator\")\n\t}\n\treturn &Iterator{h.dbName, itr}, nil\n}\n\n// Close closes the DBHandle after its db data have been deleted\nfunc (h *DBHandle) Close() {\n\tif h.closeFunc != nil {\n\t\th.closeFunc()\n\t}\n}\n\n// UpdateBatch encloses the details of multiple `updates`\ntype UpdateBatch struct {\n\tleveldbBatch *leveldb.Batch\n\tdbName       string\n\tsize         int\n}\n","sourceCodeStart":282,"sourceCodeEnd":318,"githubUrl":"https://github.com/hyperledger/fabric/blob/2736b63f8fd5932511d56fe68b7039d15977f7f6/common/ledger/util/leveldbhelper/leveldb_provider.go#L282-L318","documentation":"GetIterator creates a range iterator over the handle's LevelDB DB and immediately checks itr.Error(). If obtaining the iterator itself failed (e.g. DB closed, corrupted metadata, read error), it releases the iterator and returns this wrapped error. All range queries over txIDs and metadata flow through here, so callers like txIDExists, IsEmpty, and deleteAll surface it.","triggerScenarios":"Calling GetIterator (directly or via Query/IsEmpty/txIDExists) on a DBHandle whose underlying DB failed to create an iterator — typically after the DB was closed/errored, corrupted MANIFEST/current files, or I/O failure at iterator creation time.","commonSituations":"Querying ledger state after an earlier LevelDB open failure or close; corrupted database directory after crash; disk-full or permission errors during iterator creation; concurrent shutdown while a query is in flight.","solutions":["Check the wrapped cause (errors.Unwrap) for the specific LevelDB failure and fix it (permissions, disk, corruption)","Ensure the DB is open and Close() has not been called before issuing queries","Restore the ledger directory from backup/snapshot if files are corrupted","Retry after resolving I/O/disk issues; serialize shutdown with in-flight queries"],"exampleFix":"// before\nitr, err := handle.GetIterator(startKey, endKey)\n// after\nitr, err := handle.GetIterator(startKey, endKey)\nif err != nil {\n\tlog.Errorf(\"iterator failed: %v\", errors.Unwrap(err))\n\treturn err // verify DB open state / fix underlying cause first\n}","handlingStrategy":"try-catch","validationCode":"if dbClosed.Load() { return errors.New(\"db already closed\") }\nif _, err := os.Stat(dbPath / \"CURRENT\"); err != nil { return fmt.Errorf(\"db not open/corrupt: %w\", err) }","typeGuard":"func isIteratorCreationError(err error) bool {\n\treturn err != nil && strings.Contains(err.Error(), \"internal leveldb error while obtaining db iterator\")\n}","tryCatchPattern":"itr, err := handle.GetIterator(start, end)\nif err != nil {\n\tcause := errors.Unwrap(err)\n\tlog.Errorf(\"iterator creation failed: %v (db open? disk ok?)\", cause)\n\treturn err\n}\ndefer itr.Release()","preventionTips":["Ensure DB Close() is never called before all queries complete","Verify database directory permissions and disk health at startup","Restore from snapshot/backup on detected corruption before querying","Serialize shutdown and query paths to avoid use-after-close"],"tags":["leveldb","iterator","database","range-query"],"backgroundTag":"leveldb-iterator-error","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"}