Hitler read the messages himself, instead of having the professional diplomats explain it to him; and Hitler read the standard diplomatic politesse and soft words as conciliatory
This is inaccurate: he consulted his foreign minister whom he considered an expert on Great Britain, but unfortunately, he appointed on this role a sycophant businessman who convinced himself and Hitler that the British were bluffing, and went so far to have “the German embassy in London provide translations from pro-appeasement newspapers such as the Daily Mail and the Daily Express for Hitler’s benefit, which had the effect of making it seem that British public opinion was more strongly against going to war for Poland than it actually was.” For more details, see https://en.wikipedia.org/wiki/Joachim_von_Ribbentrop#Pact_with_Soviet_Union_and_outbreak_of_World_War_II
This is inaccurate: he consulted his foreign minister whom he considered an expert on Great Britain, but unfortunately, he appointed on this role a sycophant businessman who convinced himself and Hitler that the British were bluffing, and went so far to have “the German embassy in London provide translations from pro-appeasement newspapers such as the Daily Mail and the Daily Express for Hitler’s benefit, which had the effect of making it seem that British public opinion was more strongly against going to war for Poland than it actually was.” For more details, see https://en.wikipedia.org/wiki/Joachim_von_Ribbentrop#Pact_with_Soviet_Union_and_outbreak_of_World_War_II