ERROR HANDLER FOR A PROXY SERVER COMPUTER SYSTEM

An error handler for a proxy server computer system receives a universal resource locator from a remote user terminal, accesses from a computer network a data file identified by the universal resource locator for supply to the user terminal, automatically modifies the universal resource locator in response to detection of a failure by the accessing means to access the data file, determines if a data file identified by the modified universal resource locator is accessible to the user terminal, and returns variable data indicating the error and offering remedial options to the user.