How to trace QRS API POST errors in Qlik Sense logs, which log file to look at?

[Dave-Ampere]

Hi, I'm trying to develop some QRS API calls to automate some processes for QlikSense on Windows (Enterprise). GET calls are working OK, but POSTs and PUTs are not. I'm getting a 400 response back but without further information.

As a first step, could you advise me the best place to look in the QlikSense logs for these calls? Also, do the logs need to be at a certain verbosity?

Thanks!

[Patricia_Silva]

Hello @Dave-Ampere, I would suggest you to set the logs to debug mode. On the other hand have you tried to use Postman tool to see what response you get from there?

[Dave-Ampere · Accepted solution]

Hi @Patricia_Silva , thanks. I do use Postman yes. The response doesn't carry enough information (a 400 code but little else).

Thanks! Your help has helped me crack it: 

I worked out it is the "System Level Log" that needed to be set to DEBUG and then I can see more information in the Repository Log folder, in the "Trace > System Repository" log.

From there I could see the JSON payload was causing an exception in QlikSense. With a bit of trial and error I've got my payload JSON correct. Sorted 🙂

Some background details:

I was testing the create flow (POST) to create a new custom property definition (as per the API docs for creating custom property ). Once I'd set the level to Debug, I could see my POST request and then the next line in the logs carries this:

[RESTEngine.HandleException] Caught Newtonsoft.Json.JsonReaderException	Unexpected character encountered while parsing value: n. Path '', line 0, position 0.	   at Newtonsoft.Json.JsonTextReader.ParseValue()↵↓   at Newtonsoft.Json.JsonReader.ReadForType(JsonContract contract, Boolean hasConverter)↵↓   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)↵↓   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)↵↓   at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)↵↓   at Qlik.Sense.Common.Serialization.JSONSerializer.Deserialize(String value, Type type, JsonSerializerSettings serializerSettings)↵↓   at Qlik.Sense.Common.Communication.REST.Server.RESTParser.ParseRequest(IHttpListenerRequestWrapper httpRequest, IHttpRecording httpRecording, IObjectCreator objectCreator, ParsedMethod parsedMethod)↵↓   at Qlik.Sense.Common.Communication.REST.Server.RESTEngine.<>c__DisplayClass26_0.<GetParsedRequest>b__0(ParsedMethod parsedMethod)↵↓   at System.Collections.Generic.List`1.ForEach(Action`1 action)↵↓   at Qlik.Sense.Common.Communication.REST.Server.RESTEngine.GetParsedRequest(IHttpListenerRequestWrapper request, IHttpRecording httpRecording, IObjectCreator objectCreator)↵↓   at Qlik.Sense.Common.Communication.REST.Server.RESTEngine.HandleRequest(IHttpListenerRequestWrapper httpRequest, IHttpListenerResponseWrapper httpResponse, IHttpRecording httpRecording)

[Patricia_Silva]

Hello @Dave-Ampere, I am happy to know the issue could be solved, and also happy that you shared the solution you found 🙂