> For the complete documentation index, see [llms.txt](https://docs.digibee.com/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.digibee.com/documentation/troubleshooting/integration-issues/timeout-pipeline-executor.md).

# Timeout in the Pipeline Executor connector

## **Why does the timeout occur?**

In a synchronous call from the [Pipeline Executor](/documentation/connectors-and-triggers/connectors/tools/pipeline-executor.md) connector, the origin pipeline waits for the destination pipeline to complete and return a response before it continues.

The **Timeout** value doesn't just measure how long the destination pipeline takes to process the message. It measures the whole round trip:

1. The origin pipeline sends the message.
2. The message waits in the destination pipeline's queue.
3. The destination pipeline processes the message.
4. The response goes back to the origin pipeline's queue.
5. The origin pipeline receives the response and continues.

Queue time counts toward the timeout in both directions. When the destination pipeline receives a high volume of executions, messages wait longer in its queue, and the response can take longer to reach the origin pipeline than the configured timeout allows, even if the destination pipeline itself finishes processing in time. When this happens, the destination pipeline returns a timeout error to the origin pipeline.

{% hint style="info" %}
Even if the destination pipeline responds in under a second, the origin pipeline can still time out if queue delays make the round trip longer than the configured **Timeout** value.
{% endhint %}

This typically happens when the number of calls exceeds the processing capacity of the destination pipeline, and results in an error like this:

{% code overflow="wrap" %}

```
The message could not be sent to the specified pipeline. Error org.apache.camel.ExchangeTimedOutException: The OUT message was not received within: 20000 millis due reply message with correlationID: Camel-…-… not received on destination: amq.gen-…. Exchange[…-…]
```

{% endcode %}

## **Common causes**

Check if your pipelines fit one of these scenarios:

| Scenario                                                                                       | What happens                                                                                                                        |
| ---------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- |
| The origin pipeline is deployed with more concurrent executions than the destination pipeline. | The origin pipeline can send more requests than the destination pipeline can process, so requests queue up on the destination side. |
| The destination pipeline is triggered by multiple flows at the same time.                      | The combined requests exceed the concurrent executions allowed in the destination pipeline's deployment.                            |

Each deploy type allows a different maximum number of concurrent executions:

| Deploy type | Maximum concurrent executions |
| ----------- | ----------------------------- |
| Small       | 10                            |
| Medium      | 20                            |
| Large       | 40                            |

A mismatch between the origin and destination pipeline's deploy type is a common cause of this error. Watch for combinations like these:

| Origin pipeline | Destination pipeline |
| --------------- | -------------------- |
| Medium          | Small                |
| Large           | Medium               |
| Large           | Small                |

## **Solution**

Apply one of these fixes:

* Increase the number of concurrent executions of the destination pipeline so it can handle more requests. This may require increasing the number of replicas.
* If the operation can be asynchronous, change it to ASYNC, or use an event-based call so the queue manager controls traffic to the destination pipeline.

To learn more about how Pipeline Executor timeout works, read [Pipeline Executor](/documentation/connectors-and-triggers/connectors/tools/pipeline-executor.md).


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