Most of the PF (Provident fund) website users getting error while registering Digital signature on the website. One of the reason for error will be Java settings. It is advised to use Java 7 update 55 or lesser for lesser settings. If your system doesn't support these version better to install latest version of Java do the following settings in Java control panel.
Use only Internet explorer or Firefox. It will not work on Google Chrome.
Most of the common error screenshot will be as follows: