InvalidParameter

InvalidParameter refers to an error condition in which a parameter supplied to a function, method, or API call is not valid. In many programming environments this condition is represented by an exception type or error code named InvalidParameter, or by language-specific equivalents such as InvalidArgument or IllegalArgumentException. The exact representation varies by language and framework, but the core idea remains: the caller provided input that violates the operation’s contract.

Common causes include missing required parameters, null values where non-null are required, values outside allowed range, incorrect types, or formats that do not conform to expected patterns. Some APIs also enforce inter-parameter constraints, for example a start date that must precede an end date. Validation is often performed at the boundary of a function or API to detect invalid inputs early.

Handling typically involves raising or returning an InvalidParameter condition with a descriptive message. In APIs, this is often accompanied by an appropriate status and a structured error body, such as HTTP 400 Bad Request with details about the offending parameter. For example, a function setAge(age) would signal InvalidParameter if age is negative.

Best practices emphasize fail-fast behavior and clear diagnostics. Provide precise error messages that identify the offending parameter and the nature of the violation, avoid leaking sensitive information, and keep validation logic consistent and well-documented. Where possible, centralize validation and expose parameter requirements in API specifications or developer documentation.

See also: input validation, argument exception, illegal argument, E_INVALIDARG, invalid_argument.