{"record":{"id":"d62d778c4bf0c58e","repo":"vitessio/vitess","slug":"context-canceled-updating-tablet-type-for-s-in-th","errorCode":null,"errorMessage":"context canceled updating tablet_type for %s in the topo, please retry","messagePattern":"context canceled updating tablet_type for (.+?) in the topo, please retry","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"go/vt/vttablet/tabletmanager/tm_state.go","lineNumber":226,"sourceCode":"func (ts *tmState) ChangeTabletType(ctx context.Context, tabletType topodatapb.TabletType, action DBAction) error {\n\tts.mu.Lock()\n\tdefer ts.mu.Unlock()\n\tlog.Info(fmt.Sprintf(\"Changing Tablet Type: %v for %s\", tabletType, ts.tablet.Alias.String()))\n\n\tvar primaryTermStartTime *vttime.Time\n\tif tabletType == topodatapb.TabletType_PRIMARY {\n\t\tprimaryTermStartTime = protoutil.TimeToProto(time.Now())\n\n\t\t// Update the tablet record first.\n\t\t_, err := topotools.ChangeType(ctx, ts.tm.TopoServer, ts.tm.tabletAlias, tabletType, primaryTermStartTime)\n\t\tif err != nil {\n\t\t\tlog.Error(fmt.Sprintf(\"Error changing type in topo record for tablet %s :- %v\\nWill keep trying to read from the toposerver\", topoproto.TabletAliasString(ts.tm.tabletAlias), err))\n\t\t\t// In case of a topo error, we aren't sure if the data has been written or not.\n\t\t\t// We must read the data again and verify whether the previous write succeeded or not.\n\t\t\t// The only way to guarantee safety is to keep retrying read until we succeed\n\t\t\tfor {\n\t\t\t\tif ctx.Err() != nil {\n\t\t\t\t\treturn fmt.Errorf(\"context canceled updating tablet_type for %s in the topo, please retry\", ts.tm.tabletAlias)\n\t\t\t\t}\n\t\t\t\tti, errInReading := ts.tm.TopoServer.GetTablet(ctx, ts.tm.tabletAlias)\n\t\t\t\tif errInReading != nil {\n\t\t\t\t\t<-time.After(100 * time.Millisecond)\n\t\t\t\t\tcontinue\n\t\t\t\t}\n\t\t\t\tif ti.Type == tabletType && proto.Equal(ti.PrimaryTermStartTime, primaryTermStartTime) {\n\t\t\t\t\tlog.Info(\"Tablet record in toposerver matches, continuing operation\")\n\t\t\t\t\tbreak\n\t\t\t\t}\n\t\t\t\tlog.Error(\"Tablet record read from toposerver does not match what we attempted to write, canceling operation\")\n\t\t\t\treturn err\n\t\t\t}\n\t\t}\n\t}\n\n\terr := ts.updateTypeAndPublish(ctx, tabletType, primaryTermStartTime, action)\n\treturn err","sourceCodeStart":208,"sourceCodeEnd":244,"githubUrl":"https://github.com/vitessio/vitess/blob/01a25a7d176f94613b8d59d799f438380a8760e4/go/vt/vttablet/tabletmanager/tm_state.go#L208-L244","documentation":"During ChangeTabletType, after a topo write error the tablet retries reading the record to confirm whether the write landed; if the context is canceled while still looping, it returns this error telling the caller to retry. Vitess must verify the write because a topo error leaves success unknown.","triggerScenarios":"changeTypeLocked, setReplicationSourceLocked, ReplicaWasRestarted, or endPrimaryTerm triggers a topo tablet_type update that errors, and the caller's context (deadline/cancel) expires during the retry-read loop in ts.updateState.","commonSituations":"Graceful shutdown (PRSetType during tablet stop) cancels the context mid-retry; short client deadlines on vtctldclient ChangeTabletType during topo instability; etcd/zookeeper outage slowing reads beyond the deadline.","solutions":["Retry ChangeTabletType with a fresh, longer-lived context","Check topo server health (etcd/zk connectivity) if retries keep failing","Avoid shutting down the tablet while a type change is in flight; complete the type change first","Inspect the tablet's current type with vtctldclient GetTablet to see if the earlier write actually succeeded"],"exampleFix":"// before\ntm.ChangeTabletType(ctx, ...)\n// after: retry with a fresh context and verify final state\nfor i := 0; i < 3; i++ {\n    err := tm.ChangeTabletType(ctx2, ...)\n    if err == nil { break }\n    if ctx2.Err() != nil { ctx2 = context.Background(); }\n}","handlingStrategy":"retry","validationCode":"if ctx.Err() != nil {\n    return fmt.Errorf(\"aborting before ChangeTabletType: %w\", ctx.Err())\n}","typeGuard":null,"tryCatchPattern":"if strings.Contains(err.Error(), \"context canceled updating tablet_type\") {\n    // verify current type then retry with a fresh context\n    t, _ := topo.GetTablet(ctx2, alias)\n    if t.Type != wantType { tm.ChangeTabletType(ctx2, wantType) }\n}","preventionTips":["Use generous deadlines for type changes; avoid canceling during PRSetType","Complete type changes before shutting tablets down","Monitor topo server (etcd/zk) latency and health","Verify final tablet type after any canceled change"],"tags":["topology","context-cancel","tablet-type"],"backgroundTag":"context-canceled","analyzedSha":"01a25a7d176f94613b8d59d799f438380a8760e4","analyzedAt":"2026-09-01T17:28:30.605Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}