Workflow errors

Errors for Workflows might be raised, for example, by failed HTTP requests, functions, connectors, or generated by your own workflow code.

Error maps

When a workflow throws an error during execution that isn't caught, the execution fails, and an error map (a JSON dictionary) describing the error is returned.

Errors thrown during workflow execution contain tags to help you identify what caused the error. For example, the error returned from a connector can have two keys (tags and message) similar to the following:

{'tags': ['SystemError'], 'message': 'an error has occurred'}

There can be more than one tag. To check for a specific tag, you can use an expression. For example:

${'SystemError' in e.tags}

Access error data returned as a string

Some connectors and HTTP APIs will serialize errors as strings before returning the errors. You can use standard library functions to restore a payload to the original error. For example, to convert an error string to a map, you can use the json.decode and text.encode functions:

json.decode(text.encode(ERROR_FROM_API))

Error tags

The following table describes the meaning of different error tags.

Tag Description
AuthError Raised when generating credentials for an HTTP request fails.
ConnectionError Raised when a connection is successfully established with the endpoint but there is a problem with the connection during data transfer. The connection is terminated before a full response is received and a message might not have been delivered to the endpoint. Retries might not be idempotent.
ConnectionFailedError Raised when a connection is not established with the API endpoint; for example, due to an incorrect domain name, DNS resolution issues, or other network problems. Retries are idempotent.
HttpError Raised when an HTTP request fails with an HTTP error status. When this exception is raised, the response is a map with the following elements:
  • tags—list with HttpError string
  • message—human-readable error message
  • code—HTTP response status code
  • headers—response headers
  • body—response body
IndexError Raised when a sequence subscript is an out of range integer.
KeyError Raised when a map key is not found in the set of existing keys.
OperationError Raised when a long-running operation finishes unsuccessfully.
ParallelNestingError Raised when the maximum depth that parallel steps can be nested is exceeded.
RecursionError Raised when the interpreter detects that the maximum call stack depth is exceeded.
ResourceLimitError Raised when some resource limit is exhausted. When raised internally, this type of error cannot be caught and causes immediate execution failure.
ResponseTypeError Raised when a long-running operation returns a response of the wrong type.
SystemError Raised when the interpreter finds an internal error.
TimeoutError Raised when a system function times out at the system level.
TypeError Raised when an operation or function is applied to an object of incompatible type. The associated value is a string giving details about the type mismatch.
UnhandledBranchError Raised when one or more branches or iterations encounters an unhandled runtime error up to a maximum number.
ValueError Raised when an operation or function receives an argument that has the correct type but an incorrect value, and the situation is not described by a more precise exception, such as an IndexError.
ZeroDivisionError Raised when the second argument of a division or modulo operation is zero. The associated value is a string indicating the type of the operands and the operation.

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