In MINIT: /* Replace error handler callback with our own */ xdebug_old_error_cb = zend_error_cb; xdebug_new_error_cb = xdebug_error_cb; In MSHUTDOWN: zend_error_cb = xdebug_old_error_cb; %xdebug_error_cb%: /* Error callback for formatting stack traces */ void xdebug_error_cb(int type, const char *error_filename, const uint error_lineno, const char *format, va_list args) { ... }