The Weimar republic was already from the beginning weak, because it had to pay reparations for the First World War, but the real crisis came in 1920s when Weimar republic had to face many problems all together. At first, the basic thing as constitution had many mistakes and therefore government was so weak. However, every stronger party in Reichstag wanted to use the weakness of government to their own good and become the strongest party in Germany, the political chaos and revolts raised in state. Finally in 1923 Germany faced its next problem, when the economic crisis hit Germany.
In early 1920's, the Weimar government was so weak, and the biggest reason of its weakness was proportional representation of parties in it. Proportional representation means, that amount of members of one party represented in Reichstag, depended on percentage of votes gained in elections. This caused, that in Reichstag were 29 parties represented and therefore we couldn't speak about compact and solid government, because these parties were different oriented so they often couldn't concur.
Karte des Deutschen Reiches, »Weimarer Republik/D...
English: Map of the Weimar Republic in 1930.
ReichstagNext problem of constitution's weakness was Article 48, which was enacted in 1919. This article gave president so-called sole power whenever he want. President could use this article in emergency situation and have law of veto. So if president was different oriented than leading party in Reichstag, that could cause many conflicts like later, in 1930's when was president Hindenburg in charge and the leading party was NAZI party. Hindenburg didn't accept any of NAZI law offers, so people started to hate Paul von Hindenburg, because NAZI party was the most popular. Finally, next reason was, that important state institutions like judges and army didn't cooperate with government. . In early1920s had bigger representation in Reichstag Social democrats. Army led by Paul von Seekt didn't cooperate...