Please help, Why was the Treaty of Versailles unfair

Because Germany was forced to take sole responsibility of the war despite the fact it was actually Austria-Hungary that was the sole perpetrator of the war when it chose to declare war on Serbia in late July 1914 following the Serbian terrorist group assassination of Archduke Franz Ferdinand a month earlier. They were also forced to pay huge demand and leased territories to Britain and France, and reduced its military manpower at the lowest level as possible. This caused the Germans to be angry, isolated, and desperate and the Great Depression helped wrecked the German economy. The result of the Treaty of Versailles was the rise of Hitler and the Nazi Party in the 1930s and led to the Second World War. Had not for the harsh provisions imposed upon Germany, the Second World War and the rise of the Nazis in the 1930s might not even happened.

Both countries had to aprove annexation.