{"record":{"id":"36c4762b3485a53c","repo":"hyperledger/fabric","slug":"failed-to-get-any-blocks-from-syncbuffer","errorCode":null,"errorMessage":"failed to get any blocks from SyncBuffer","messagePattern":"failed to get any blocks from SyncBuffer","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"orderer/consensus/smartbft/synchronizer_bft.go","lineNumber":118,"sourceCode":"\t// === Create a buffer to accept the blocks delivered from the BFTDeliverer.\n\tcapacityBlocks := max(uint(s.LocalConfigCluster.ReplicationBufferSize)/uint(s.Support.SharedConfig().BatchSize().AbsoluteMaxBytes), 100)\n\ts.mutex.Lock()\n\ts.syncBuff = NewSyncBuffer(capacityBlocks)\n\ts.mutex.Unlock()\n\n\t// === Create the BFT block deliverer and start a go-routine that fetches block and inserts them into the syncBuffer.\n\tbftDeliverer, err := s.createBFTDeliverer(startHeight, myEndpoint)\n\tif err != nil {\n\t\treturn nil, errors.Wrapf(err, \"cannot create BFT block deliverer\")\n\t}\n\n\tgo bftDeliverer.DeliverBlocks()\n\tdefer bftDeliverer.Stop()\n\n\t// === Loop on sync-buffer and pull blocks, writing them to the ledger, returning the last block pulled.\n\tlastPulledBlock, err := s.getBlocksFromSyncBuffer(startHeight, targetHeight)\n\tif err != nil {\n\t\treturn nil, errors.Wrapf(err, \"failed to get any blocks from SyncBuffer\")\n\t}\n\n\tdecision := s.BlockToDecision(lastPulledBlock)\n\ts.Logger.Infof(\"Returning decision from block [%d], decision: %+v\", lastPulledBlock.GetHeader().GetNumber(), decision)\n\treturn decision, nil\n}\n\n// detectTargetHeight probes remote endpoints and detects what is the target height this node needs to reach. It also\n// detects the self-endpoint.\n//\n// In BFT it is highly recommended that the channel/orderer-endpoints (for delivery & broadcast) map 1:1 to the\n// channel/orderers/consenters (for cluster consensus), that is, every consenter should be represented by a\n// delivery endpoint. This important for Sync to work properly.\nfunc (s *BFTSynchronizer) detectTargetHeight() (uint64, string, error) {\n\tblockPuller, err := s.BlockPullerFactory.CreateBlockPuller(s.Support, s.ClusterDialer, s.LocalConfigCluster, s.CryptoProvider)\n\tif err != nil {\n\t\treturn 0, \"\", errors.Wrap(err, \"cannot get create BlockPuller\")\n\t}","sourceCodeStart":100,"sourceCodeEnd":136,"githubUrl":"https://github.com/hyperledger/fabric/blob/2736b63f8fd5932511d56fe68b7039d15977f7f6/orderer/consensus/smartbft/synchronizer_bft.go#L100-L136","documentation":"Raised in BFTSynchronizer.synchronize when s.getBlocksFromSyncBuffer(startHeight, targetHeight) returns an error — the BFTDeliverer goroutine was started but the sync buffer yielded no usable blocks, so block replication failed entirely. The message is slightly misleading: it wraps any error from the buffer consumption loop, not only an empty buffer.","triggerScenarios":"DeliverBlocks runs but fails to push any block into s.syncBuff (all deliver connections fail, remote peers reject the range, context cancelled), or getBlocksFromSyncBuffer aborts (buffer closed early, expected sequence mismatch, ledger write failure on the first block).","commonSituations":"Network interruption right after sync starts; remote peers rejecting Deliver due to TLS/certificate auth; peers not holding blocks in [startHeight, targetHeight); sync buffer closed because the deliverer hit a fatal error; ledger write errors (disk full).","solutions":["Look at deliverer logs just before this error for the real failure (deliver stream error, buffer close cause)","Verify remote peers are reachable over the cluster port and hold blocks from startHeight onward","Fix TLS/authorization for the Deliver service and retry synchronization","Check local disk space and ledger health if the failure occurred on WriteBlock"],"exampleFix":null,"handlingStrategy":"retry","validationCode":"// Ensure peers hold the full needed range before syncing\nstartHeight := support.Height()\nif minPeerHeight(consenters) < startHeight+1 || maxPeerHeight(consenters) < startHeight+1 {\n    // no peer can serve the first needed block yet\n}","typeGuard":null,"tryCatchPattern":"resp := bftSynchronizer.Sync()\nif syncFailed(resp) {\n    // transient deliver/buffer failure — retry with backoff\n    time.Sleep(backoff)\n    resp = bftSynchronizer.Sync()\n}","preventionTips":["Monitor deliverer goroutine health and buffer fills during catch-up","Guarantee stable network to a quorum of peers before triggering sync","Watch disk space so ledger writes don't abort the buffer loop","Alert on repeated empty sync-buffer failures as a sign of deliver-stream auth issues"],"tags":["consensus","smartbft","fabric","block-replication","network"],"backgroundTag":"block-pull-failed","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"}