<p>MySQL raises ER_SP_DUP_HANDLER when a stored program declares more than one identical DECLARE HANDLER within the same BEGIN ... END block.</p>
<p>MySQL Error 1413 ER_SP_DUP_HANDLER occurs when a stored procedure, function, trigger, or event defines the same EXIT, CONTINUE, or UNDO handler twice in one block. Remove or move the duplicate handler to an inner block to resolve the issue.</p>
Duplicate handler declared in the same block
MySQL raises ER_SP_DUP_HANDLER when a stored procedure, function, trigger, or event defines more than one DECLARE HANDLER with the same condition or SQLSTATE inside the same BEGIN ... END block. The server stops compilation because only one handler of a given type can exist per block.
The error prevents ambiguous flow control logic at runtime. MySQL must know exactly which handler to invoke for a given condition, so duplicate declarations are rejected during the parsing phase, not during execution.
The error surfaces at CREATE PROCEDURE time or when you execute an anonymous compound statement. It never appears during runtime because the server refuses to compile the code until the duplication is removed.
It is common when developers copy and paste template code, wrap statements in nested blocks incorrectly, or refactor handlers without deleting older ones.
Compilation halts, so the stored program cannot be created or altered. Automated deployments fail, CI pipelines stop, and scheduled jobs that rely on the procedure might break. Fixing the duplication restores deploy velocity and eliminates downtime.
Duplicate DECLARE HANDLER statements for the same SQLSTATE, error code, or condition name in a single BEGIN ... END block trigger the error.
Declaring both EXIT and CONTINUE handlers for an identical condition without nesting blocks also counts as duplication.
Identify handlers that share the same condition, then keep one and remove or rename the rest.
Alternatively, move the second handler into its own inner BEGIN ... END block so each block has a single unique handler scope.
If you need different behaviors, use separate SQLSTATE codes or wrap logic in sub blocks.
If you only changed the handler action, merge the two into one handler that performs both tasks.
Document all handlers at the top of each block, conduct code reviews, and enable linting in Galaxy or your CI pipeline to catch duplicates before deployment.
Use consistent templates where each block clearly scopes its handlers to reduce copy paste mistakes.
ER_SP_UNDECLARED_VAR appears when a variable is referenced before it is declared in the same block. The fix is to reorder declarations.
ER_SP_VARCOND_AFTER_CURSHNDLR occurs when variables are declared after a cursor or handler. Move variable declarations above.
Two DECLARE HANDLER statements use the same SQLSTATE value such as '02000' inside one BEGIN ... END block.
Developers duplicate a code template that already contains a handler, forgetting to remove the original.
Both an EXIT and a CONTINUE handler target the same condition at the same block level, producing a conflict.
Raised when a variable is used before being declared in the same block.
Occurs when DECLARE statements follow a cursor or handler within the same block.
Appears when a stored procedure has two parameters with identical names.
Yes, as long as each targets a different SQLSTATE, error code, or condition name. Only duplicates are forbidden.
No. EXIT, CONTINUE, and UNDO are considered duplicates if they share the same condition within the same block.
Yes. A nested BEGIN ... END block has its own scope, so you can redeclare the same handler there safely.
Galaxy highlights duplicate handler declarations, offers AI fixes, and lets you test code quickly to prevent deployment failures.
.avif)
.avif){kind=logo}
