{"record":{"id":"b57579721c186f6d","repo":"hyperledger/fabric","slug":"empty-block-or-block-header-channel-s","errorCode":null,"errorMessage":"empty block or block header, channel: %s","messagePattern":"empty block or block header, channel: (.+?)","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"orderer/consensus/smartbft/sync_buffer.go","lineNumber":35,"sourceCode":"\tblockCh  chan *common.Block\n\tstopCh   chan struct{}\n\tstopOnce sync.Once\n}\n\nfunc NewSyncBuffer(capacity uint) *SyncBuffer {\n\tif capacity == 0 {\n\t\tcapacity = 10\n\t}\n\treturn &SyncBuffer{\n\t\tblockCh: make(chan *common.Block, capacity),\n\t\tstopCh:  make(chan struct{}),\n\t}\n}\n\n// HandleBlock gives the block to the next stage of processing after fetching it from a remote orderer.\nfunc (sb *SyncBuffer) HandleBlock(channelID string, block *common.Block) error {\n\tif block == nil || block.Header == nil {\n\t\treturn errors.Errorf(\"empty block or block header, channel: %s\", channelID)\n\t}\n\n\tselect {\n\tcase sb.blockCh <- block:\n\t\treturn nil\n\tcase <-sb.stopCh:\n\t\treturn errors.Errorf(\"SyncBuffer stopping, channel: %s\", channelID)\n\t}\n}\n\nfunc (sb *SyncBuffer) PullBlock(seq uint64) *common.Block {\n\tvar block *common.Block\n\tfor {\n\t\tselect {\n\t\tcase block = <-sb.blockCh:\n\t\t\tif block == nil || block.Header == nil {\n\t\t\t\treturn nil\n\t\t\t}","sourceCodeStart":17,"sourceCodeEnd":53,"githubUrl":"https://github.com/hyperledger/fabric/blob/2736b63f8fd5932511d56fe68b7039d15977f7f6/orderer/consensus/smartbft/sync_buffer.go#L17-L53","documentation":"SyncBuffer.HandleBlock forwards blocks fetched from remote orderers into an internal channel for the next processing stage. If the fetched block is nil or lacks a Header, it is unusable and this error is returned instead of enqueueing garbage downstream.","triggerScenarios":"The block puller delivers a nil block or a headerless block from a remote orderer during synchronization — e.g. a remote endpoint returning an empty/garbage response for the requested sequence.","commonSituations":"A misbehaving or misconfigured remote orderer endpoint (wrong port, a non-orderer service) returning malformed blocks; a puller hitting an endpoint whose ledger is empty or corrupted; race where a stopped/starting node returns empty results.","solutions":["Verify BlockPuller endpoint configuration (TLS certs, endpoints, ports) points at healthy orderers of the channel.","Remove/unhealthy endpoints: prune HeightsByEndpoints targets that return bad data and re-sync from a good consenter.","Check the remote orderer's ledger health at the requested height; repair or re-join it if its ledger is corrupted.","Retry synchronization — transient bad responses from one endpoint are typically bypassed on the next attempt."],"exampleFix":"// before\n// endpoints include a stale node returning empty blocks\nLocalConfigCluster.SendBufferSize = 10 // endpoints unchanged\n\n// after\n// remove stale endpoints from cluster.* config and restart orderer\n// cluster.replication.endpoints = [healthy-orderer1:7050, healthy-orderer2:7050]","handlingStrategy":"validation","validationCode":"func safeHandleBlock(sb *SyncBuffer, channelID string, b *common.Block) error {\n    if b == nil || b.Header == nil {\n        return fmt.Errorf(\"skip nil/headerless block on %s\", channelID)\n    }\n    return sb.HandleBlock(channelID, b)\n}","typeGuard":"func isUsableBlock(b *common.Block) bool {\n    return b != nil && b.Header != nil\n}","tryCatchPattern":"err := sb.HandleBlock(channelID, block)\nif err != nil && strings.Contains(err.Error(), \"empty block or block header\") {\n    // remote endpoint returned garbage: drop endpoint and retry sync\n    return retrySyncWithoutEndpoint(badEndpoint)\n}","preventionTips":["Keep cluster.replication.endpoints pointing only at healthy, correct orderers.","Verify TLS and port configuration of every puller endpoint.","Monitor HeightsByEndpoints results for endpoints returning zero/nil heights.","Health-check peer ledgers before including them in replication targets."],"tags":["hyperledger-fabric","smartbft","sync","block-puller"],"backgroundTag":"invalid-block-received","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"}