A complicated question. Here's a simplified answer.
The short term answer is the change from a silver to a dual standard, as gold fell in silver terms when the California gold rush brought enormous (in terms of existing stocks of gold) quantities of new gold on the market. Austria had financial problems. The dual standard was subject to automatic inflation that would have helped Austria to repay its debt. However, both its allies and its arch-enemy, Prussia did not agree; important, because the successive customs unions were a game for influence and economic domination of the German speaking world that Austria could not afford to lose. Yet, in the currency treaty of Vienna (1857), the possibility was opened to coin gold Kronen coins. That same treaty signalled the end of the Austrian Gulden, in favour of the Prussian Taler.
Austria got in deeper financial trouble and issued paper money that devalued quickly, revamped its money only to see the same cycle of financial problems and reform happen again. In the end, the gold Krone became a silver coin that was introduced as the standard in the umpteenth currency reform, that held only until the next war.
The long term answer is the changing nature of warfare. For centuries, Austria (and Russia, but that is another story) were front line states, in almost constant war with the Ottoman empire. The Ottomans gradually lost that ongoing war, so it was a source of income by plunder for the Austrian state, while the cost was highest for the population of the farming villages on both sides that happened to be in the way of an army. The size of armies was restricted by the quantity of food it could carry and steal and how long it took for a contagious disease to break out. Arms were amazingly imprecise and ineffective.
Better medical care after the French revolution and the introduction of the potato made it possible to raise much larger armies for much longer. The rifled barrel made war far more deadly. These developments meant that war had become significantly more costly. Austria was not prepared for that change. The Crimean war (1853 - 1857) came when Austria had not yet recovered from the Napoleonic wars and exhausted the country financially. It brought about the spiral described above, ending only with the first world war.
In a larger framework, Austria, a hotchpotch of nationalities and cultures, was useful only as long as the Ottomans were a threat. When that was no longer the case, the empire slowly but inevitably fell apart into its constituent nationalities.
Peter
