vitessio/vitess · error

target shard %v has no primary tablet

Error message

target shard %v has no primary tablet

What it means

buildResharder requires every target shard to have a primary tablet (PrimaryAlias set) so the vreplication streams have somewhere to replicate into. If a target shard has no elected primary, this error names the shard and aborts ReshardCreate.

Source

Thrown at go/vt/vtctl/workflow/resharder.go:112

			return nil, vterrors.Wrapf(err, "GetShard(%s) failed", shard)
		}
		if !si.IsPrimaryServing {
			return nil, fmt.Errorf("source shard %v is not in serving state", shard)
		}
		rs.sourceShards = append(rs.sourceShards, si)
		primary, err := s.ts.GetTablet(ctx, si.PrimaryAlias)
		if err != nil {
			return nil, vterrors.Wrapf(err, "GetTablet(%s) failed", si.PrimaryAlias)
		}
		rs.sourcePrimaries[si.ShardName()] = primary
	}
	for _, shard := range targets {
		si, err := s.ts.GetShard(ctx, keyspace, shard)
		if err != nil {
			return nil, vterrors.Wrapf(err, "GetShard(%s) failed", shard)
		}
		if si.PrimaryAlias == nil {
			return nil, fmt.Errorf("target shard %v has no primary tablet", shard)
		}
		if si.IsPrimaryServing {
			return nil, fmt.Errorf("target shard %v is in serving state", shard)
		}
		rs.targetShards = append(rs.targetShards, si)
		primary, err := s.ts.GetTablet(ctx, si.PrimaryAlias)
		if err != nil {
			return nil, vterrors.Wrapf(err, "GetTablet(%s) failed", si.PrimaryAlias)
		}
		rs.targetPrimaries[si.ShardName()] = primary
	}
	if err := topotools.ValidateForReshard(rs.sourceShards, rs.targetShards); err != nil {
		return nil, vterrors.Wrap(err, "ValidateForReshard")
	}
	if err := rs.validateTargets(ctx); err != nil {
		return nil, vterrors.Wrap(err, "validateTargets")
	}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Initialize the shard's primary: `vtctl InitShardPrimary <keyspace>/<shard> <tablet-alias>` (or force flag as appropriate)
2. Verify with `vtctl GetShard <keyspace>/<shard>` that PrimaryAlias is now set before re-running Reshard
3. Bring up/repair the missing target tablet so it can be promoted

Example fix

// before (shard 40- has no primary)
Reshard --source-shards=0- --target-shards=0-40,40-
// after
vtctl InitShardPrimary ks/40- zone1-0000000100
Reshard --source-shards=0- --target-shards=0-40,40-

for _, shard := range targetShards {
    si, err := ts.GetShard(ctx, ks, shard)
    if err != nil { return err }
    if si.PrimaryAlias == nil {
        return fmt.Errorf("pre-check: target shard %s has no primary; run InitShardPrimary", shard)
    }
}

if _, err := reshardCreate(ctx, req); err != nil {
    if strings.Contains(err.Error(), "has no primary tablet") {
        // init the shard primary, then retry ReshardCreate
    }
    return err
}

When it happens

Trigger: ReshardCreate targets new shards whose primaries were not initialized — e.g. target tablets registered but InitShardPrimary never run on one of the new shards.

Common situations: New shards created for the split but one target tablet failed to start before Reshard; forgotten InitShardPrimary on a fresh shard; target tablet in a bad state so no primary was elected.

Related errors

• source shard %v is not in serving state
• target shard %v is in serving state
• VReplication stream has the same workflow name as the reshar
• VReplication stream has the same workflow name as the reshar
• no primary tablet found for materialization workflow %s and

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/d5e140c0e3f81f04. Report an issue: GitHub.