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Informix Error -437

-437 Connection must be established before registering callback function.

You attempted to register a callback function before you connected to a database server. You must first connect to a database server and then register your callback function.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-437 is a straightforward sequencing error in the same ESQL/C callback-registration mechanism as -435/-436: the callback registration call was made before a database server connection was actually established.

  1. Callback registration code executed before CONNECT/DATABASE — a plain ordering mistake.
  2. Application startup logic that registers callbacks and connects to the database in the wrong order, perhaps due to a refactor that moved one step without the other.
Solutions / Resolution
  1. Establish the database server connection first, then register the callback function, per the official guidance — this is a required sequence, not a suggestion.
  2. Review application startup logic for the correct ordering if this appeared after a refactor.
Examples
Correct ordering
EXEC SQL CONNECT TO 'sales@server1';
/* now register the callback, with connection established */
/* register_callback(timeout, callback_fn); */
The disallowed reversed ordering
/* register_callback(timeout, callback_fn); */
/* -437: no connection established yet */
EXEC SQL CONNECT TO 'sales@server1';
Diagnostic Checks
  1. Check the order of operations in application startup code — confirm CONNECT/DATABASE runs before callback registration.
Related Errors / Related Topics
  • -436 — "Call back function must be defined when time-out value is 0 or greater." A related restriction in the same callback-registration mechanism, about required arguments rather than sequencing.
  • -349 — "Database not selected yet." A related session-sequencing error, in the more general SQL-statement context rather than this specific callback-registration mechanism.

Establish the connection first — callback registration always needs an existing connection to attach to.