While Europe was advancing technologically, Ottomans were left behind.
Ottomans had a very wide border and territory to protect, so when rebellions of local populations by the provocation and the support of various European countries started, Ottomans lacked the money and military power to quell them all. You see, the known world was all colonized by these countries and lacking new places to invade, they decided to take the Ottoman Empire apart and share its lands among themselves.)))