There's actually a long history of bear taming, both in Europe and Asia and bears generally seem to be quite tameable and trainable.
However, there hasn't ever been the overlapping situation of species, culture and environment that would push people into domestication. Don't mean it's impossible, it just means that the dice didn't shake out that way.
First thing you need to look at is possible economic utility. What do bears got that humans want?
Besides their gall bladders?
Traditionally, what do we get from big domesticates: 1) Meat, 2) Milk, 3) Eggs, 4) Wool, 5) Fur/Leather, 6) Draft Labour/pack carrying/cart or plow pulling, 7) Other labour, 8) Pest control.
Now, onto bears. Milk, Eggs, Wool and pest control are pretty much out of the running.
Leaves us with Meat, Fur/Leather, and Labour. Now, when you look at this, there's something to be said. Bear meat is edible, and even tasty. Black bears are comparable to pork, although not quite as nutritious. Bears are pretty strong, and in season appear capable of reasonable levels of sustained activity. And they make a good coat.
But this has to be cost effective. ie, the social or economic investment in domesticated bear meat, fur/leather and labour has to produce a return that makes it worthwhile.
How do we assess worth? In comparison to other alternatives. For instance - harvesting wild bears, using other domesticates, balancing the consumption of bears with the output.
Now some bears are more expensive than others. Polar bears are pure carnivores. Pandas are pure herbivores, but so specialized that they're almost useless. Brown bears are omnivores. Black bears are mostly herbivore/opportunist/omnivores with a diet that overlaps with swine.
Now, while bears may have potential as a food animal, or a draft labour animal, one of their problems is that they do poorly compared to the baseline domesticates - cattle and horses. Cattle and horses are much cheaper to keep, their work output is greater, and they produce milk. Cattle and horses are the powerhouse duo. They make it tough for the rest of the domesticates.
But other big domesticates do compete. We have Yak, Water Buffalo, Reindeer, Camel, Llama. What's their secret? These animals thrive where cattle and horses are either absent or difficult to sustain effectively. ie, they've found niches where through history or environment, the big competitors couldn't go.
So that's one option for bears. To domesticate bears, you need either an environmental situation, or a historical circumstance, which precludes or handicaps competing domesticates. Why domesticate a bear if you already have swine... or sheep... or cattle or horses...
Bears are comparable to swine in terms of their diet and in terms of the value of their flesh, but they're not economically competitive with swine normally. So you would need special circumstances, which causes them to replace swine. ie, a situation where raising bears is easier and cheaper than swine.