500 Error on 'Finish & Sync' with custom source connector built with low-code builder UI

Summary

Encountering a 500 error with a custom source connector built using a low-code builder UI, resulting in a NullPointerException related to JSON handling in the airbyte-server-container output.


Question

:red_circle: Title: 500 Error on “Finish & Sync” with a custom source connector built with low-code builder UI (see picture)

:question: What I’m doing: Testing a custom source connector (<https://app.makosoftware.de/docs/api/|Makoflow API>) built with the Builder Web UI running locally via abctl install

:eyes: Error Message from airbyte-server-container output from crictl logs container-id``

java.lang.NullPointerException: Cannot invoke "com.fasterxml.jackson.databind.JsonNode.fieldNames()" because the return value of "com.fasterxml.jackson.databind.JsonNode.get(String)" is null
	at io.airbyte.commons.server.validation.CatalogValidator.fieldCount(CatalogValidator.kt:39) ~[io.airbyte-airbyte-commons-server-0.61.0.jar:?]
	at io.airbyte.commons.server.handlers.ConnectionsHandler.validateCatalogSize(ConnectionsHandler.java:1172) ~[io.airbyte-airbyte-commons-server-0.61.0.jar:?]
	at io.airbyte.commons.server.handlers.ConnectionsHandler.createConnection(ConnectionsHandler.java:507) ~[io.airbyte-airbyte-commons-server-0.61.0.jar:?]
	at io.airbyte.commons.server.handlers.WebBackendConnectionsHandler.webBackendCreateConnection(WebBackendConnectionsHandler.java:564) ~[io.airbyte-airbyte-commons-server-0.61.0.jar:?]
	at io.airbyte.server.apis.WebBackendApiController.lambda$webBackendCreateConnection$1(WebBackendApiController.java:88) ~[io.airbyte-airbyte-server-0.61.0.jar:?]
	at io.airbyte.server.apis.ApiHelper.execute(ApiHelper.java:28) ~[io.airbyte-airbyte-server-0.61.0.jar:?]
	at io.airbyte.server.apis.WebBackendApiController.webBackendCreateConnection(WebBackendApiController.java:86) ~[io.airbyte-airbyte-server-0.61.0.jar:?]
	at io.airbyte.server.apis.$WebBackendApiController$Definition$Exec.dispatch(Unknown Source) ~[io.airbyte-airbyte-server-0.61.0.jar:?]
	at io.micronaut.context.AbstractExecutableMethodsDefinition$DispatchedExecutableMethod.invokeUnsafe(AbstractExecutableMethodsDefinition.java:461) ~[micronaut-inject-4.4.8.jar:4.4.8]
	at io.micronaut.context.DefaultBeanContext$BeanContextUnsafeExecutionHandle.invokeUnsafe(DefaultBeanContext.java:4232) ~[micronaut-inject-4.4.8.jar:4.4.8]
	at io.micronaut.web.router.AbstractRouteMatch.execute(AbstractRouteMatch.java:271) ~[micronaut-router-4.4.8.jar:4.4.8]
	at io.micronaut.http.server.RouteExecutor.executeRouteAndConvertBody(RouteExecutor.java:488) ~[micronaut-http-server-4.4.8.jar:4.4.8]
	at io.micronaut.http.server.RouteExecutor.lambda$callRoute$6(RouteExecutor.java:465) ~[micronaut-http-server-4.4.8.jar:4.4.8]
	at io.micronaut.core.execution.ExecutionFlow.lambda$async$1(ExecutionFlow.java:87) ~[micronaut-core-4.4.8.jar:4.4.8]
	at io.micronaut.core.propagation.PropagatedContext.lambda$wrap$3(PropagatedContext.java:211) ~[micronaut-core-4.4.8.jar:4.4.8]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
	at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]```
See thread for source connector YAML

:green_heart: *Call to action: Has anyone experienced this 500 error (null value instead of json) output from airbyte-server-container when setting up a new custom source connector?*

(could it be related to the fact that little or no data is available at some of the source API endpoints ?) ... IDK

:pray: any comments, thoughts, suggstions welcome! THANK YOU!!

<br>

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["500-error", "custom-source-connector", "low-code-builder", "null-pointer-exception", "json-handling", "airbyte-server-container"]
</sub>