Question

What did Hitler do that was in violation of the Treaty of versailles??

Answer 1

The first way Hitler broke the Treaty was over Germany’s armed forces.   In 1934, he destroyed the League of Nations Disarmament Conference by demanding equality of arms with France and Britain – this broke the Treaty because it had set up the League with the stated aim of achieving disarmament. The second way Hitler broke the Treaty was over the Rhineland (declared a demilitarised zone).  The third way Hitler broke the Treaty of Versailles occurred in 1938.   The Treaty forbade Anschluss between Germany and Austria. An attempted Nazi putsch in Austria failed in 1934, but in 1938 Hitler tried again.

Answer 2

Stopped Paying Reparations
The Treaty of Versailles said Germany had to pay 6.6 billion pounds over 66 years to help pay for damages caused by the war.
Hitler stopped paying the reparations and put the money back into the German economy. 
Again, no one did anything in order to keep peace.
Rebuilt Germany's Army
In 1935, Hitler restarted the conscription process in Germany and built up Germany's air force and navy.
Even though these things were in direct violation of the Treat of Versailles, no one acted against Hitler because they were trying to practice policies of appeasement.