The standard view about dark matter is as a halos associated with galaxies and also other astrophysical objects. Nature however seems to be reluctant to behave according to the dictates of halo theorists. The reproduction of the simple flat velocity spectrum for distant stars in galactic plane requires tuning of the parameters characterizing the dark mass distribution in the halo. There is also a small constant density core around the center of galaxy behaving like rigid body rather than a density peak with maximum at the center. Also the attempts to detect various exotic particles proposed to serve as building bricks of dark matter have chronically failed. Quite recently very old galaxies which do not have dark matter have been found.
The latest trouble of the model, one might say a death blow, is that dark matter disks do not seem to exist at all (see this)! I am afraid that this means serious funding problems for the model builders.
The death of one idea is the victory of second one. I have been preaching for almost two decades that galactic dark matter along cosmic string containing galaxies like pearls in necklace: there would be no dark matter halo (see this, this, and this). The model predicts correct velocity profile for distant stars without furher assumptions: the value of string tension determines the value of the velocity. The model solvs a multitude of anomalies of halo model, and leads to a rather detailed model for evolution of galaxies and also provides insights to problems like matter-antimatter asymmetry.
See the the chapter TGD and astrophysics .