Informix Error -9403: The <modifier-name> modifier must be specified.

Reasons / Common Causes

-9403 fires when a CREATE AGGREGATE statement omits a required modifier — per the official guidance.

1. A missing ITER or COMBINE modifier, per the official guidance — the direct, only cause; the iterator (ITER) and combine (COMBINE) functions are required for all user-defined aggregates.

Solutions / Resolution

1. Include the named modifier in the CREATE AGGREGATE statement, per the official guidance.

Examples

A CREATE AGGREGATE statement missing COMBINE

CREATE AGGREGATE new_aggr WITH (ITER = iter_func);   -- -9403: COMBINE missing

Corrected

CREATE AGGREGATE new_aggr WITH (ITER = iter_func, COMBINE = combine_func);

Diagnostic Checks

1. Check the CREATE AGGREGATE statement includes both ITER and COMBINE modifiers, and add whichever is missing.

Related Errors / Related Topics

• -9402 — "Multiple occurrences of the modifier." A related modifier-validity error, on a duplicated modifier rather than a missing required one.
• -9410 — "User-defined aggregate has two arguments but no INIT function specified." A related required-modifier error, specific to INIT when a set-up argument is used.

A required modifier (ITER or COMBINE) was missing from the CREATE AGGREGATE statement — add it.