For a workaround, launch a standalone kernel and evaluate

    PacletSiteUpdate /@ PacletSites[]

    PacletUpdate["EntityFramework"]

More detailed instructions can be found [here](https://mathematica.stackexchange.com/questions/92931/mathematica-10-0-x-freezes-in-initializing-kernels) (except substitute `"CloudObject"` with `"EntityFramework"`).

Please see also [this post](http://community.wolfram.com/groups/-/m/t/1094350) on Wolfram Community for step by step instructions on all platforms.