The thanos query v0.41.0 is incompatible with the thanos sidecar in v0.34.1.

[zdyj3170101136]

Thanos, Prometheus and Golang version used:

thanos query v0.41.0,thanos sidecar v0.34.1.

Object Storage Provider:

What happened:
query thanos query, thanos sidecar would panic.

log:

ts=2026-03-25T08:06:39.080084106Z caller=recover.go:43 level=error msg="runtime panic in TSDB Series server" err="runtime error: invalid memory address or nil pointer dereference" stacktrace="goroutine 731985613 [running]:\ngithub.com/thanos-io/thanos/pkg/store.(*recoverableStoreServer).recover(0x4000a6ef60, {0x303ec30, 0x4000fb1340})\n\t/app/pkg/store/recover.go:41 +0x270\npanic({0x1cbc880?, 0x4380f00?})\n\t/usr/local/go/src/runtime/panic.go:914 +0x218\ngithub.com/thanos-io/thanos/pkg/store/storepb.(*QueryHints).IsSafeToExecute(...)\n\t/app/pkg/store/storepb/custom.go:548\ngithub.com/thanos-io/thanos/pkg/store.(*PrometheusStore).Series(0x4000a5dd60, 0x4000d98780, {0x303bc80?, 0x40000dd9a0})\n\t/app/pkg/store/prometheus.go:218 +0xa00\ngithub.com/thanos-io/thanos/pkg/store.(*instrumentedStoreServer).Series(0x4000a66cf0, 0x4001080120?, {0x303bd70?, 0x4000f08780})\n\t/app/pkg/store/telemetry.go:169 +0xa8\ngithub.com/thanos-io/thanos/pkg/store.(*limitedStoreServer).Series(0x4000a66db0, 0xffffa26a9108?, {0x303ec30?, 0x4000fb1340})\n\t/app/pkg/store/limiter.go:141 +0x1a8\ngithub.com/thanos-io/thanos/pkg/store.(*recoverableStoreServer).Series(0x4000f085d0?, 0x200b7c0?, {0x303ec30?, 0x4000fb1340?})\n\t/app/pkg/store/recover.go:28 +0x6c\ngithub.com/thanos-io/thanos/pkg/store/storepb._Store_Series_Handler({0x1df4680?, 0x4000a6ef60}, {0x3037670, 0x4000f085d0})\n\t/app/pkg/store/storepb/rpc.pb.go:1100 +0xd0\ngithub.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/logging.StreamServerInterceptor.StreamServerInterceptor.func1({0x1df4680, 0x4000a6ef60}, {0x3037670, 0x4000f085a0}, 0x4000c8d8a8, 0x2ad40c8)\n\t/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware/v2@v2.0.0-rc.2.0.20201207153454-9f6bf00c00a7/interceptors/server.go:35 +0x1d0\ngithub.com/thanos-io/thanos/pkg/server/grpc.New.WithStreamServerChain.ChainStreamServer.func12.1.1({0x1df4680?, 0x4000a6ef60?}, {0x3037670?, 0x4000f085a0?})\n\t/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware/v2@v2.0.0-rc.2.0.20201207153454-9f

What you expected to happen:

thanos sidecar could response successfully.
How to reproduce it (as minimally and precisely as possible):

Full logs to relevant components:

Anything else we need to know:

[zdyj3170101136]

in thanos v0.34.1, thanos sidecar would check hint IsSafeToExecute.

// IsSafeToExecute returns true if the function or aggregation from the query hint
// can be safely executed by the underlying Prometheus instance without affecting the
// result of the query.
func (m *QueryHints) IsSafeToExecute() bool {
	distributiveOperations := []string{
		"max",
		"max_over_time",
		"min",
		"min_over_time",
		"group",
	}
	for _, op := range distributiveOperations {
		if m.Func.Name == op {
			return true
		}
	}

	return false
}

in pr #7392, it remove the QueryHints.

but in pr https://github.com/thanos-io/thanos/pull/8625/changes, it add back the QueryHints but not set Func.Name, so it would panic if thanos sidecar is v0.34.1.

[zdyj3170101136]

the thanos v0.41.0 only compatiable with thanos sidecar >= v0.35.1

[zdyj3170101136]

It is recommended to pass func.name as an unused parameter to the queryhint:

QueryHints: &storepb.QueryHints{
			Func:              &storepb.Func{Name: ""},
			ProjectionLabels:  hints.ProjectionLabels,
			ProjectionInclude: hints.ProjectionInclude,
		},

after this, the thanos query v0.41.0 could work well with v0.34.1 thanos sidecar.

[zdyj3170101136]

@yeya24 cc