> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://docs.fynapse.app/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.fynapse.app/_mcp/server. # Flow Validations > Learn about Flow validations in Fynapse. ## Overview When you are creating a new Flow you can check if it is correct by clicking the **Validate** button. The Flow will be validated against the validation rules and a list of validation errors will appear on the right-hand side of the screen. | **Validation Rule** | **Validation Error** | | ----------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Referenced Flow does not exist | The Flow with internal ID (\{id}) does not exist. | | Referenced Flow does not have a draft | The Flow with internal ID (\{id}) does not have a draft. | | Flow has been archived | The Flow with internal ID (\{id}) was archived. | | Flow name is already used | A Flow with the following name: "\{name}) already exists. This name cannot be used again. | | Flow name must not be empty | The Name field for Flow cannot be empty. Please enter a unique name. | | Flow name is too long | The Name for a Flow cannot exceed 64 characters. | | Flow name contains non-alphanumeric characters | The Name of the "\{name}" Flow contains invalid characters. The allowed characters are: upper and lowercase letters, numbers, spaces and the following special characters: ()!\_.- | | Flow name cannot start with non letter characters | A Flow name has to start with a letter. | | Flow is incomplete | The Flow needs a single Input and at least one Target defined. All Targets need to be have their outputs defined. | | Flow has cycle | Some steps are connected in a loop. A Flow diagram cannot have cycles. | | Internal Error: Node Empty | The Node is empty, that should not be possible. Contact Fynapse Administrator. | | Internal Error: Definition is missing | The Node definition is empty, that should not be possible. Contact Fynapse Administrator. | | Step name must not be empty | The Name field of the Step is empty. | | Step name is too long | The Name for a Step cannot exceed 128 characters. | | Step name contains non-alphanumeric characters | The Name of the "\{name}" Step contains invalid characters. The allowed characters are: upper and lowercase letters, numbers, spaces and the following special characters: ()!\_.- | | Step name cannot start with non letter character | A Step name has to start with a letter. | | Data Entity is not set | The Data Entity is not set. Please select one of Entities that are defined in the system. | | Chosen Data Entity does not exist | There "\{name}" Data Entity does not exist in "\{namespace}". | | Invalid number of incoming links | The step has an invalid number of incoming links. The step can have \{expected} incoming links, but it is connected with \{got} steps. | | Invalid number of outgoing links | The step has invalid number of outgoing links. The step can have \{expected} outgoing links, but it is connected with \{got} steps. | | There's no input step defined | There can be only one Input step defined. | | More than one input step | There can be only one Input step defined. | | Circular Dependency between Flows | The Flow will create a circular dependency. The input Transactional Data Entity "from "\{namespace}" is populated by another Flow fed directly or indirectly by products of this Flow. | | Invalid Accounting Engine output | The Accounting Engine step can only be followed by the Journal Processor step. | | Invalid Journal Processor input | The Journal Processor step can be sourced only with the Accounting Engine step. | | Attribute name is empty | An attribute in the output definition is empty (path from root: "\{path}"). | | Attribute name is invalid | The ("\{name}") Attribute name is invalid, the name should start with an alphanumeric character and not contain any special characters (path from root: "\{path}"). | | Attribute name is already in use | The ("\{name}") Attribute name in the output definition is already in use (path from root: "\{path}"). | | Attribute type is not set | The ("\{name}") Attribute name has an undefined type (path from root: "\{path}"). | | Target attribute does not exist | Target attribute (path from root: "\{path}") does not exist in the Target Entity "entity name". | | Mandatory target attribute not mapped | Mandatory target attribute: " \{MandatoryAttributeName}" in the Target Entity "entity name" is not mapped to any source attribute. | | Source attribute does not exist | Source attribute (path from root: " \{MappedSourceAttributePath}") does not exist. | | Combination of params: source type, target type and context mapping flag are not allowed. | Combination of params: source type (path from root: " \{MappedSourceAttributePath} "), target type (path from root: " \{MappedTargetAttributePath}") and context mapping flag are not allowed. | | Incorrect mapping within context. | Mapping from " \{MappedSourceAttributePath}" to "\{MappedTargetAttributePath}" not possible. Cannot determine unambiguous source value. | | Script's source code has syntax error | Syntax error in script "\{ScriptName}", line "\{SyntaxErrorLine}", column "\{SyntaxErrorColumn}", error phrase "\{InvalidPhrase}". | | IOException during source extraction | IOException during source extraction from "\{ScriptName}". | | Script output attribute has invalid name | The "\{attributeName}" attribute in the "\{scriptName}" Script Step is equal to a Python keyword. Attributes cannot equal Python keywords. | | Script has no runnable code | The "\{scriptName}" Script Step has no runnable code. A Script Step has to have runnable code. |