It seems that the IMDb forums have totally disappeared from the web.
Here is their message if we go at this address :
The IMDb message boards were disabled on February 20, 2017. This included the Private Message system. IMDb is passionately committed to providing innovative ways for our hundreds of millions of users to engage and communicate with one another. We will continue to enhance our current offerings and launch new features in 2017 and beyond that will help our customers communicate and express themselves in meaningful ways while leveraging emerging technologies and opportunities.
We can suppose that they are improving their board cms script instead of just closing it because of too much hate.