The Bosnian Crisis had begun almost immediately after the Ottoman Empire entered a state of revolution. Revolution that lasted less than thirty days, mind you, before the Sultan was forced to concede to the demands of the Young Turk Movement and allow for the restoration of the Empire's Constitution, and to an extent a new election for Parliament.
As a result of this, the Balkans were thrown into turmoil, with several nations either directly under the control of other Ottoman Empire as imperial territories, or vassal states such as Bulgaria using this as a chance to gain their much-desired independence.
And, of course, the Habsburgs used this as a reason to fully annex the region known as Bosnia and Herzegovina, which had for the last few decades been under their indirect control. The moment the Austrian Army marched into the Balkans; things got chaotic very quickly.