Why didn't Adolf hitler sign the truce with Stalin?

Because he knew he was gonna break the promise and he did

Hitler did sign a truce with stalin.

" The relationship between Joseph Stalin and Adolf Hitler was a slippery slope, especially during World War II. In August of 1939, they signed a non-aggression pact. This was a truce between Germany and the Soviet union, stopping battles between the two countries. For Hitler, the pact brought a guarantee for invading Poland and other parts of Europe without any disturbance from the Soviets."