Errors detected in the PAI are signaled to the global VISTA error handling system, which allows the user to specify different error handlers for each type of error. In addition to program-signaled errors, the error system handles system faults and program exit too. The default error handler prints out the function, the line number and source file name of the function, where the error occurred.
New error handlers can be registered by each application to handle error conditions in a program specific way. For example, the caching layer installs its own exit handler on initialization to panic-close all open PBFs through the error system if a memory fault or address violation occurs.