Installing applications downloaded through the web or the WAP of the Nokia N71 mobile phone requires validated certificates to proceed. In case there is a Nokia E71 certificate error, the application will fail to install in the mobile phone. The workaround for this error is to turn off the online certificate feature of the Nokia N71 mobile phone. Alternatively, for expired certificates, changing the date and time of the phone may solve the problem. If the Nokia N71 certificate error persists, it is best to contact the application vendor to know more about the problem.