First problem can be that they lost a lot of their territories. They had to give away all their colonies and also parts of their land to others which caused a huge problem since those territories were inhabited mostly by German people who didn't support these new governments. They supported German rulers and wanted German governance so an independence struggle was inevitable.
Second can be that they were financially ruined. Because they lost all colonies and their country was devastated, they could not make any money at all. This was combined with the fact that their war reparations were so huge that they couldn't pay them off, it more or less made the whole country bankrupt. The people were enraged by this and didn't want to support such clauses.
Third was that the people felt humiliated. Because of everything that happened because of their government, they felt that they were being punished to severely for something that they didn't do since the government then was a monarchy. Their anger started rising and when Hitler showed up and talked about this, they started supporting him so it led to a huge rise in extremism.
The three major problems that came from the Treaty of Versailles was that un-payable reparations were imposed on the Germans, the Germans were forced to lose all military capabilities, and they were humiliated, which led them to seek a dictator.
a primary source is a source from the time and place of the event, like a photograph that was taken of a president from 1920. If it was something like a book written in 2015 about the picture from 1920, that would be a secondary source. Hope this helps!
