· Jun 25

custom internal server error message in REST API

Hello all,
I am creating a REST API with a spec-first approach. However, I am using the try-catch method to handle any exception if any occurs. But whenever any error related to syntax or something occurs, we get internal server error 


"errors": [


"code": 6220,

"domain": "%ObjectErrors",

"error": "ERROR #6220: Internal Server Error",

"id": "InternalError"



"summary": "ERROR #6220: Internal Server Error"



This is I think IRIS defined, I want to customize my own Internal server error. 

Discussion (6)1
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Assuming you are using generated disp and impl classes from a swagger document, the simplest option you have at the moment is to edit the code in the impl class:

  • Use try/catch within your implementation method
  • the catch block to set %response.Status = your required status code
  • Create a json object with your required payload
  • return this object instead of the usual payload object

This will bypass the default error handling of the disp class.

It isn't ideal though.


ClassMethod myFunction(arg1 As %Integer) As %Stream.Object
    try {
        set ret = {"data": "value" }
        if 1/0 // Force an error
    catch err {
        set ret = ##class(SomeClass).FormatError(err)
        Set %response.Status = 500

    quit ret

However, it would be even more helpful to be able to override the default error display. This would need some changes to the dispatch and implementation class generators.

The dispatch class generator would need to call the specific implementation class to format the error, instead of the implementation superclass.

The implementation class generator also (really) needs to be able to accept an override for the implementation superclass via the swagger document (as there is for the dispatch class).

Then the try/catch would not be needed at all, and the default error handling would do everything needed.

This is as of Iris 2022.1. I'm not sure if this has been added in later versions.