<p>Error 1644 occurs when a SIGNAL statement raises an exception that no HANDLER intercepts inside a stored procedure, function, trigger, or event.</p>
<p>MySQL Error 1644: ER_SIGNAL_EXCEPTION happens when a user-issued SIGNAL raises an unhandled exception inside stored code. Add the right DECLARE ... HANDLER or remove the SIGNAL to resolve the error.</p>
Unhandled user-defined exception condition
MySQL raises Error 1644 with condition name ER_SIGNAL_EXCEPTION when a stored procedure, function, trigger, or event executes the SIGNAL statement and no HANDLER catches the resulting exception. The server aborts the current statement, rolls back, and returns SQLSTATE HY000 with the custom message.
The error always originates from user code that explicitly executes SIGNAL or RESIGNAL. Typical reasons include input validation failures, business rule violations, or debugging placeholders left in code.
If a CONTINUE or EXIT handler for the raised condition is missing or incorrectly scoped, the exception remains unhandled, letting Error 1644 propagate to the client.
Locate the exact SIGNAL statement by searching your stored program or examining the message text returned. Decide whether the logic should really abort or whether it should recover.
Add an appropriate DECLARE ... HANDLER inside the same block or an outer block to intercept the condition. Alternatively, remove or alter the SIGNAL if the business rule has changed.
Triggers that enforce complex constraints often raise SIGNAL but forget to declare handlers for ON DUPLICATE actions, leading to uncaught exceptions during bulk inserts.
Stored procedures that validate JSON input may SIGNAL an error when a key is missing. Wrapping the call inside a TRY-CATCH wrapper procedure with a SQLEXCEPTION handler logs the error and returns a friendly code.
Always pair every SIGNAL with a matching CONTINUE or EXIT handler that either rolls back gracefully or converts the condition to a result set.
Use Galaxy's linting in its SQL editor to flag naked SIGNAL statements during development, enabling teams to catch the issue before deployment.
Error 1336: NEW_SYM - occurs when referencing NEW or OLD outside a trigger. Check trigger context.
Error 1172: ER_SIGNAL_EXCEPTION_IN_TRIGGER - arises within triggers when SIGNAL is used but mishandled. The fixes mirror Error 1644.
No DECLARE ... HANDLER for the raised SQLSTATE lets the exception bubble up.
Business rule incorrectly flags valid data and raises SIGNAL unnecessarily.
Developer added SIGNAL for debugging and forgot to remove it.
HANDLER declared inside inner block while SIGNAL occurs outside its scope, leaving it uncaught.
SIGNAL statement specifies a nonstandard or mistyped SQLSTATE, treated as unhandled.
Same root cause but limited to trigger context; handled identically.
Occurs when NEW or OLD pseudo-rows are misused; unlike 1644 it is a syntax issue, corrected by fixing trigger logic.
Raised when SIGNAL references an undefined condition name; declare the condition first.
Search all procedures, triggers, and events for the MESSAGE_TEXT returned with the error; Galaxy's global search accelerates this.
No, SIGNAL is part of SQL/PSM; you must modify offending code or add handlers.
A CONTINUE handler can prevent rollback by consuming the error, but you must manage transactional consistency manually.
The behavior is unchanged; however, GET DIAGNOSTICS provides richer context for debugging.
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