{"record":{"id":"8340babada3522b0","repo":"vitessio/vitess","slug":"did-not-received-expected-fields-in-response-v-o","errorCode":null,"errorMessage":"did not received expected fields in response %+v on tablet %v","messagePattern":"did not received expected fields in response %\\+v on tablet (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"go/vt/vttablet/tabletmanager/vdiff/table_differ.go","lineNumber":466,"sourceCode":"\t\t}\n\t\tvar fields []*querypb.Field\n\t\treq := &binlogdatapb.VStreamRowsRequest{\n\t\t\t// We pass the NoTimeouts options as otherwise the row streamer will add a MAX_EXECUTION_TIME\n\t\t\t// query hint with a value based on the --vreplication-copy-phase-duration flag.\n\t\t\tTarget: target, Query: query, Lastpk: lastPK, Options: &binlogdatapb.VStreamOptions{NoTimeouts: true},\n\t\t}\n\t\treturn conn.VStreamRows(ctx, req, func(vsrRaw *binlogdatapb.VStreamRowsResponse) error {\n\t\t\t// We clone (deep copy) the VStreamRowsResponse -- which contains a vstream packet with N rows and\n\t\t\t// their corresponding GTID position/snapshot along with the LastPK in the row set -- so that we\n\t\t\t// can safely process it while the next VStreamRowsResponse message is getting prepared by the\n\t\t\t// shardStreamer. Without doing this, we would have to serialize the row processing by using\n\t\t\t// unbuffered channels which would present a major performance bottleneck.\n\t\t\t// This need arises from the gRPC VStreamRowsResponse pooling and re-use/recycling done for\n\t\t\t// gRPCQueryClient.VStreamRows() in vttablet/grpctabletconn/conn.\n\t\t\tvsr := vsrRaw.CloneVT()\n\t\t\tif len(fields) == 0 {\n\t\t\t\tif len(vsr.Fields) == 0 {\n\t\t\t\t\treturn fmt.Errorf(\"did not received expected fields in response %+v on tablet %v\",\n\t\t\t\t\t\tvsr, td.wd.ct.vde.thisTablet.Alias)\n\t\t\t\t}\n\t\t\t\tfields = vsr.Fields\n\t\t\t\tgtidch <- vsr.Gtid\n\t\t\t}\n\t\t\tif len(vsr.Rows) == 0 && len(vsr.Fields) == 0 {\n\t\t\t\treturn nil\n\t\t\t}\n\t\t\tp3qr := &querypb.QueryResult{\n\t\t\t\tFields: fields,\n\t\t\t\tRows:   vsr.Rows,\n\t\t\t}\n\t\t\tresult := sqltypes.Proto3ToResult(p3qr)\n\n\t\t\t// Fields should be received only once, and sent only once.\n\t\t\tif len(vsr.Fields) == 0 {\n\t\t\t\tresult.Fields = nil\n\t\t\t}","sourceCodeStart":448,"sourceCodeEnd":484,"githubUrl":"https://github.com/vitessio/vitess/blob/01a25a7d176f94613b8d59d799f438380a8760e4/go/vt/vttablet/tabletmanager/vdiff/table_differ.go#L448-L484","documentation":"In the differ's VStreamRows loop, the first response must carry field metadata; if the first streamed response has neither cached fields nor vsr.Fields, the differ cannot decode subsequent rows and returns this error with the offending response and tablet alias. (The typo 'did not received' is in the source.)","triggerScenarios":"The first VStreamRows response from the target arrives with empty Fields and no previously cached fields — e.g. a protocol/RPC anomaly, response pooling bug, or the stream erroring right at start.","commonSituations":"gRPC connection issues between target differ and vttablet; mixed-version cluster where response reuse/recycling misbehaves; target tablet restarted mid-stream so fields never arrive.","solutions":["Retry the vdiff; transient RPC glitches often resolve on a fresh stream.","Check tablet logs around the time for VStreamRows errors and version skew between vtctld/vttablet.","Upgrade to a consistent Vitess version across components; if reproducible, file an issue with the tablet logs."],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"err := runTableDiff()\nif err != nil && strings.Contains(err.Error(), \"did not received expected fields\") {\n  // transient stream/protocol issue; retry once with backoff\n  time.Sleep(2 * time.Second)\n  err = runTableDiff()\n}","preventionTips":["Run consistent Vitess versions across vtctld and vttablets.","Retry the vdiff once on this error before investigating deeper.","Monitor tablet logs for VStreamRows anomalies.","Avoid restarting target tablets mid-vdiff."],"tags":["vdiff","vstream","grpc","protocol"],"backgroundTag":"stream-missing-field-metadata","analyzedSha":"01a25a7d176f94613b8d59d799f438380a8760e4","analyzedAt":"2026-09-01T17:28:30.605Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}