When a user trying to register Digital Signature Certificate (DSC) on Income Tax e-filing Website, the error displayed "Invalid Digital Signature Certificate. The trusted Parent Certificate could not be verified" or as shown in following image:
Solution: The Digital Signature Certificate (DSC) you are using is not of Class II Digital Signature Certificate (DSC). Either it may be Class I or Class III Digital Signature Certificate (DSC). So please use Class II Digital Signature Certificate on Income Tax Website.