A technique is described for generating error buffer that includes errors from both a program and event handlers called by the program. A program in an event-driven environment triggers an event. In response to the triggered event, the program calls event handlers related to the event. The event handlers are executed and error messages generated during the execution are stored in a local error buffer. Upon completion of the event handlers, the local error buffers are returned to the program and the program merges the local error buffers with an error buffer associated with the program.