{"record":{"id":"3a461096cd593a55","repo":"vitessio/vitess","slug":"failed-reading-tablet-v-v","errorCode":null,"errorMessage":"failed reading tablet %v: %v","messagePattern":"failed reading tablet (.+?): (.+?)","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"go/vt/vtctl/vtctl.go","lineNumber":1157,"sourceCode":"\t\treturn errors.New(\"the <tablet alias> and <db type> arguments are required for the ChangeTabletType command\")\n\t}\n\n\ttabletAlias, err := topoproto.ParseTabletAlias(subFlags.Arg(0))\n\tif err != nil {\n\t\treturn err\n\t}\n\tnewType, err := parseTabletType(subFlags.Arg(1), topoproto.AllTabletTypes)\n\tif err != nil {\n\t\treturn err\n\t}\n\n\tctx, cancel := context.WithTimeout(ctx, topo.RemoteOperationTimeout)\n\tdefer cancel()\n\n\tif *dryRun {\n\t\tti, err := wr.TopoServer().GetTablet(ctx, tabletAlias)\n\t\tif err != nil {\n\t\t\treturn fmt.Errorf(\"failed reading tablet %v: %v\", tabletAlias, err)\n\t\t}\n\t\tif !topo.IsTrivialTypeChange(ti.Type, newType) {\n\t\t\treturn fmt.Errorf(\"invalid type transition %v: %v -> %v\", tabletAlias, ti.Type, newType)\n\t\t}\n\t\twr.Logger().Printf(\"- %v\\n\", fmtTabletAwkable(ti))\n\t\tti.Type = newType\n\t\twr.Logger().Printf(\"+ %v\\n\", fmtTabletAwkable(ti))\n\t\treturn nil\n\t}\n\treturn wr.ChangeTabletType(ctx, tabletAlias, newType)\n}\n\nfunc commandPing(ctx context.Context, wr *wrangler.Wrangler, subFlags *pflag.FlagSet, args []string) error {\n\tif err := subFlags.Parse(args); err != nil {\n\t\treturn err\n\t}\n\tif subFlags.NArg() != 1 {\n\t\treturn errors.New(\"the <tablet alias> argument is required for the Ping command\")","sourceCodeStart":1139,"sourceCodeEnd":1175,"githubUrl":"https://github.com/vitessio/vitess/blob/01a25a7d176f94613b8d59d799f438380a8760e4/go/vt/vtctl/vtctl.go#L1139-L1175","documentation":"In commandChangeTabletType's dry-run path, the tablet record is fetched from the topo server before simulating the type change. This error wraps a failed topo GetTablet call, meaning the tablet alias could not be read — usually because the tablet doesn't exist or the topo server is unavailable.","triggerScenarios":"Running `vtctl ChangeTabletType --dry-run <alias> <type>` where the alias is wrong/misspelled, the tablet was deleted from the topo, or the topo server errors while reading the tablet record.","commonSituations":"Stale tablet alias after the tablet was decommissioned; alias built with wrong cell/uid; topo connectivity issues in CI; DNS/etcd misconfiguration.","solutions":["Verify the alias with `vtctl GetTablet <alias>` and correct it if wrong","List tablets with `vtctl ListAllTablets <cell>` to find the right alias","Check topo server connectivity and configuration","If the tablet was removed, recreate/repair it or drop the command from the runbook"],"exampleFix":"// before\nvtctl ChangeTabletType -dry-run zone1-000000100 REPLICA  # uid typo\n// after\nvtctl ListAllTablets zone1 | grep -i replica\nvtctl ChangeTabletType -dry-run zone1-0000000100 REPLICA\n","handlingStrategy":"validation","validationCode":"# Ensure the tablet alias resolves before changing type\nif ! vtctl GetTablet \"$ALIAS\" >/dev/null 2>&1; then\n  echo \"tablet $ALIAS not found in topo\"; exit 1\nfi","typeGuard":null,"tryCatchPattern":"if err := runVtctl(\"ChangeTabletType\", \"--dry-run\", alias, tt); err != nil {\n    if strings.Contains(err.Error(), \"failed reading tablet\") {\n        // verify alias/topo; re-list tablets in the cell to find valid aliases\n    }\n}","preventionTips":["Resolve aliases from ListAllTablets rather than hardcoding uids","Health-check topo connectivity before batch tablet operations","Re-verify aliases after tablet decommissioning/replacement","Include the cell name in alias construction helpers to avoid malformed aliases"],"tags":["vtctl","topo","tablet","dry-run"],"backgroundTag":"tablet-not-found","analyzedSha":"01a25a7d176f94613b8d59d799f438380a8760e4","analyzedAt":"2026-09-01T17:28:30.605Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-08T10:18:20.063Z"}