KB-1570 "Could not cast from <variable type 1> to <variable type 2>" error thrown when interacting with a SAIL interface


When either interacting with or submitting a SAIL interface, the following error is returned:

Could not display interface. Please check definition and inputs.
Interface Definition: Expression evaluation error: An error occurred while executing a save: Could not cast from <variable_type_1> to <variable_type_2>. Details: CastInvalid


There is a saveInto parameter within a component in this SAIL interface or within a sub-rule of this interface that is attempting to cast from one variable type to another, and the fields between the two data types do not match.


Check the saveInto parameters and ensure that variables are writing correctly and are mapping to identical data types. If attempting to update only one field of a particular CDT variable, use dot notation in the target to save the singular value (e.g., ri!variableName.fieldName).

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: April 2018