The error is consistent with an undefined object reference:

$object->method(@arguments);
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If $object is undefined (if this were a database handle, I'd check to be sure the connection succeeded), you will receive an error message saying "Can't call method 'method' on an undefined value..."

Since we're almost certainly talking about a database handle, I would examine your code around the area in question (or where that code is being called in your own code) and be certain that the object you're passing is defined.