Error Setting SIGQUIT Handler. Procedure " procedure name" : " error message". Unknown message level " message level. The event handler settings are stored in the environment variable NumericEventHandlers, but should be set only by using the NumericEventHandler function. · As we can see the message is pretty much clear “ There is a duplicate. Locking is either by default. Error Parser Error Message: Unknown. · Therefore I' m creating a custom signature handler plugin. because the default handler is doing. When I trigger the validation I get an error message. vendor/ symfony/ debug/ ErrorHandler.