# PrometheusTargetLimitHit alert: what it means and how to fix it

What the PrometheusTargetLimitHit Prometheus alert means, its common causes, the PromQL rule and the runbook steps to fix it, with a ready-to-use rule in YAML.

Last reviewed 2026-10-31

A scrape job discovered more targets than its `target_limit` allows. Prometheus does not scrape just the first N in that case: it marks every target of that scrape pool as failed and scrapes none of them. A whole job goes dark at once, and its `up` series turn to 0.

* **Severity**: Warning (`warning`)
* **Fires after**: 15m
* Part of the [Prometheus alert rules](https://n9e.github.io/alert-rules/prometheus.md) (`prometheus.yml`)

## The rule[​](#the-rule "Direct link to The rule")

```
increase(prometheus_target_scrape_pool_exceeded_target_limit_total{job="prometheus-k8s",namespace="monitoring"}[5m]) > 0
```

Alert message: `Prometheus {{$labels.namespace}}/{{$labels.pod}} has dropped {{ printf "%.0f" $value }} targets because the number of targets exceeded the configured target_limit.`

## Common causes[​](#common-causes "Direct link to Common causes")

* A ServiceMonitor or PodMonitor selector is too broad and now matches Services or Pods it was not meant to.
* The monitored workload scaled out past the limit, for example a large DaemonSet or an HPA scaling out.
* Relabeling that used to drop unwanted targets was changed or removed.
* The limit was set for a smaller cluster and never revisited.

## How to fix it[​](#how-to-fix-it "Direct link to How to fix it")

1. Confirm the current target count against the limit on the /targets page;
2. Check whether the ServiceMonitor selector is too broad and picking up unwanted targets;
3. Tighten the selector or split across multiple Prometheus instances by business domain;
4. If more targets are genuinely needed, raise target\_limit and size the resources accordingly.

## Notes[​](#notes "Direct link to Notes")

* The `/targets` page shows the affected job with an error that mentions the target limit. With the Operator, the limit can come from `targetLimit` on a ServiceMonitor or PodMonitor, or `enforcedTargetLimit` on the Prometheus resource.
* The expression selects `job="prometheus-k8s"`, `namespace="monitoring"`. If your scrape job or namespace is named differently, change these matchers or the rule never matches.

## Metrics it uses[​](#metrics-it-uses "Direct link to Metrics it uses")

* `prometheus_target_scrape_pool_exceeded_target_limit_total` (Prometheus's own metrics)

## Related alerts[​](#related-alerts "Direct link to Related alerts")

* [PrometheusScrapeSampleLimitHit](https://n9e.github.io/alert-rules/prometheus.md#prometheusscrapesamplelimithit): Prometheus …/… has failed … scrapes in the last 5m because some targets exceeded the configured sample\_limit.
* [PrometheusLabelLimitHit](https://n9e.github.io/alert-rules/prometheus.md#prometheuslabellimithit): Prometheus …/… has dropped … targets because some samples exceeded the configured label\_limit, label\_name\_length\_limit or label\_value\_length\_limit.
* [PrometheusTargetSyncFailure](https://n9e.github.io/alert-rules/prometheus.md#prometheustargetsyncfailure): … targets in Prometheus …/… have failed to sync because invalid configuration was supplied.

## Prometheus rule YAML[​](#prometheus-rule-yaml "Direct link to Prometheus rule YAML")

Add this to a rules file loaded through `rule_files`, or download every Prometheus rule at once as [`prometheus.yml`](https://n9e.github.io/alert-rules/prometheus.yml).

```
- alert: PrometheusTargetLimitHit

  expr: |-

    increase(prometheus_target_scrape_pool_exceeded_target_limit_total{job="prometheus-k8s",namespace="monitoring"}[5m]) > 0

  for: 15m

  labels:

    severity: warning

  annotations:

    summary: "Prometheus {{$labels.namespace}}/{{$labels.pod}} has dropped {{ printf \"%.0f\" $value }} targets because the number of targets exceeded the configured target_limit."

    runbook_url: "https://n9e.github.io/alert-rules/prometheus/prometheustargetlimithit"
```

**With Nightingale**: this rule ships in the [Kubernetes integration](https://n9e.github.io/integrations/kubernetes.md) template; [import it into a business group](https://n9e.github.io/docs/data/integrations/import.md) and Nightingale attaches the runbook to every alert it sends.

## Sources and license[​](#sources-and-license "Direct link to Sources and license")

The rule expression is adapted from [kube-prometheus](https://github.com/prometheus-operator/kube-prometheus) (Apache-2.0). The runbook steps come from [Nightingale's integration templates](https://github.com/ccfos/nightingale/tree/main/integrations) (Apache-2.0); the explanation and causes are written for this page.