when building a connector through the UI builder, I'm getting this error for an asynchronous request:

Internal Server Error: com.fasterxml.jackson.databind.JsonMappingException: String value length (20054016) exceeds the maximum allowed (20000000, from `StreamReadConstraints.getMaxStringLength()`) (through reference chain: io.airbyte.connectorbuilderserver.api.client.model.generated.StreamRead["slices"]->java.util.ArrayList[0]->io.airbyte.connectorbuilderserver.api.client.model.generated.StreamReadSlicesInner["pages"]->java.util.ArrayList[0]->io.airbyte.connectorbuilderserver.api.client.model.generated.StreamReadSlicesInnerPagesInner["response"]->io.airbyte.connectorbuilderserver.api.client.model.generated.HttpResponse["body"])

This error is coming from Jackson’s

StreamReadConstraints

limit on maximum string length while the Connector Builder server is trying to deserialize the HTTP response body from your async stream test. The body of at least one response is ~20,054,016 characters, which exceeds the current limit of 20,000,000, so deserialization fails before the UI can show you the “Request/Response” test output. From the available docs, there is no documented way in the Connector Builder UI to change or override this Jackson limit, and there is no mention of configuration flags or workarounds for this constraint. The documentation only describes how to configure and test asynchronous streams (Creation / Polling / Download) and how to inspect requests and responses in the testing panels; it does not cover payload size limits or Jackson configuration for the builder backend.[[Async Job streams](https://docs.airbyte.com/platform/connector-development/connector-builder-ui/async-streams); [Testing async streams](https://docs.airbyte.com/platform/connector-development/connector-builder-ui/async-streams#testing-asynchronous-streams-in-the-ui)] Because of that, I can’t give you a documented, supported setting you can change to raise that 20,000,000‑character limit from the UI or standard configuration; the knowledge sources simply don’t describe such an option. Given that: - This looks analogous to the

StreamReadConstraints

/

JsonMappingException

reported for other Airbyte components when very large JSON values are processed.[[GCS issue 51592](https://github.com/airbytehq/airbyte/issues/51592)] - The error occurs during testing of the Connector Builder stream (not during a normal sync), where the builder server records entire responses for inspection. The only actionable, documentation-backed guidance I can provide is: 1. Reduce the size of the async response, if possible For example: - Narrow the date range or filter parameters in your async job creation so each exported file/response is smaller. - If your API supports pagination or splitting the export into multiple smaller jobs, configure that via query params or body in the Creation tab and/or use a Partition Router so each slice is smaller.[[Async Job streams](https://docs.airbyte.com/platform/connector-development/connector-builder-ui/async-streams)] 2. Use the “Other Requests” panel to verify earlier stages Since the failure is on the big download response body, you can still: - Verify job creation and polling are correct in the Other Requests panel (creation and polling are usually much smaller JSONs).[[Testing async streams](https://docs.airbyte.com/platform/connector-development/connector-builder-ui/async-streams#testing-asynchronous-streams-in-the-ui)] - Ensure the download URL and parameters are right even if the UI cannot safely deserialize and display the huge body. 3. If reducing the payload isn’t feasible, treat this as a product limitation and open an issue The knowledge sources do not mention any configuration to raise

StreamReadConstraints.getMaxStringLength()

for the Connector Builder server, so increasing the limit would require a code or configuration change on Airbyte’s side. Given the similarity to the open

destination-gcs

issue with

JsonMappingException

from

StreamReadConstraints

, it’s reasonable to treat this as a bug/limitation and report it with: - Your connector definition (especially the async Download configuration), - Approximate response size, - The exact error message you shared.[[GCS issue 51592](https://github.com/airbytehq/airbyte/issues/51592)] To summarize: based on the docs, there is no documented knob in the UI to avoid this error other than making the async download response smaller; anything beyond that (like relaxing the Jackson constraint) is not covered in the current knowledge sources and would require a fix or change by the Airbyte team.