The invention relates to error messaging in HTTP based communication systems. An intermediate device (20) interconnecting a wireless client terminal (10) and a web server (30) transforms error messages sent from the server before transmitting them to the client. Hereby, a first error status code from the server is transformed into an error description message comprising an error description text and second status code. The second status code preferably enforces display of the error description text at the client terminal. The invention is with advantage implemented in a proxy server (20) through an error information table (22) providing resource-location dependent error messages.