C# function error handling

If a handler reports a C# function runtime or loading error, the runtime environment automatically captures the error and returns a JSON document with the error type in the response. For more information about the JSON document format, see Calling a function.

The error data is also written to the execution log. You can view it using the Yandex Cloud CLI or the management console.

Examples of error handlingExamples of error handling

Case 1: user code goes outside the array boundaries, an IndexOutOfRangeException is thrown. The runtime environment captures the exception and generates a JSON document that contains an error message (the errorMessage field), error type (the errorType field), and stack trace (the stackTrace field).

Function code:

public class Handler {
  public int FunctionHandler(byte[] input) {
    readonly var array = new int[]{1, 2, 3, 4, 5};
    // at this point, the function throws an IndexOutOfRangeException
    return array[15];
  }
}

JSON document returned:

{
  "errorMessage": "Index was outside the bounds of the array",
  "errorType": "System.IndexOutOfRangeException",
  "stackTrace": [
    ...
  ]
}

Case 2: user code indicates an error by throwing an exception from the function.

Function code:

public class Handler {
  public int FunctionHandler(byte[] input) {
    throw new SystemException("Some error message");
  }
}

JSON document returned:

{
  "errorMessage": "Some error message",
  "errorType": "System.SystemException",
  "stackTrace": [
    ...
  ]
}