What is a Galactic Eclipse?
Definitely a hoax as other commenters have said.

Dark rifts exist in the galaxy - large clouds of dust, several can be made out by eye, overlapping the milky way, in ideal conditions.  See for example the Great Rift.  However these are so large it would take far longer than three days for a solar system to pass through them.  Probably thousands or millions of years.  So this is definitely incorrect information.