[Yandex Cloud documentation](../../../../index.md) > [Monium](../../../index.md) > Data delivery > [Unified Agent](index.md) > Possible errors

# Possible errors Yandex Unified Agent

This section describes typical problems occurring when using Unified Agent and their solutions.

In case of an error, make sure you have the latest Unified Agent version installed. To install the latest agent version, follow [this guide](../../../../monitoring/concepts/data-collection/unified-agent/installation.md#setup).

Unified Agent data retrieval and transmission errors fall under two categories:

* `ERROR agent/[plugin_id]...`: Errors that occur when retrieving metrics from the data source app. `plugin_id`: ID of the agent’s data retrieval [plugin](../../../../monitoring/concepts/data-collection/unified-agent/inputs.md).

* `ERROR agent/output-yc_metrics...`: Errors that occur when sending metrics to Monium.Metrics.

#### Message size [value] is greater than inflight limit [value], message dropped {#message-size-error}

The incoming message size exceeds the `inflight.limit` configured in the `flow_control` session buffer [settings](../../../../monitoring/concepts/data-collection/unified-agent/services.md#flow_control). This error often occurs in `gRPC input`. 

Try increasing the `flow_control.inflight.limit` value.

If the error persists, contact [support](https://center.yandex.cloud/support).

#### Timed out while bytes receiving {#time-out-error}

The data transfer has timed out.

Make sure your network connection is stable and try again.

If the error persists, contact [support](https://center.yandex.cloud/support).

#### 500 Internal server error {#internal-error}

An internal server error occured, preventing request processing. Try again.

If the error persists, contact [support](https://center.yandex.cloud/support).

#### SSL library returned error {#ssl-error}

Wrong [TLS certificate](../../../../certificate-manager/concepts/index.md) or error when establishing a secure connection. Try again.

If the error persists, contact [support](https://center.yandex.cloud/support).