#C01AHCD885S upstream prematurely closed connection while reading response header from upstream, client: 10.20.142.122, server: localhost, request: "POST /api/v1/connections/sync HTTP/1.1", upstream:

Based on the information provided in the knowledge sources, it appears you're encountering an issue with Airbyte where the upstream connection is closing prematurely. This type of error can occur for various reasons, but a few potential causes and solutions can be identified from the available information: 1. Timeout issues: The error message suggests a timeout problem, which could be related to Nginx configuration or network issues. This is similar to the error reported in [this forum post](https://discuss.airbyte.io/t/2429), where an Nginx reverse proxy was timing out. 2. Large response handling: The error might be related to handling large responses. As mentioned in [this GitHub issue](https://github.com/airbytehq/airbyte/issues/34814), Airbyte may struggle with responses over a certain size (around 25 MB in the reported case). 3. Connection reset: The error could be due to a connection reset, as seen in [this GitHub issue](https://github.com/airbytehq/airbyte/issues/34198). To troubleshoot this issue, you could try the following: 1. Check and possibly increase timeout settings in your Nginx configuration if you're using Nginx as a reverse proxy. 2. Ensure you're using the latest version of Airbyte, as older versions may have unresolved issues. 3. If you're dealing with large datasets, consider implementing pagination or partitioning to reduce the size of individual responses. 4. Check your network stability and firewall settings to ensure they're not interfering with the connection. If the problem persists after trying these steps, you may need to gather more detailed logs and potentially report the issue to the Airbyte community or support channels for further assistance.