BUDAPEST — Europe’s failure to fashion even the beginnings of a unified solution to the migrant crisis is intensifying confusion and desperation all along the multicontinent trail and breeding animosity among nations extending back to the Middle East.

With the volume of people leaving Syria, Afghanistan and other countries showing no signs of ebbing, the lack of governmental leadership has left thousands of individuals and families on their own and reacting day by day to changing circumstances and conflicting messages, most recently on Thursday when crowds that had been trying to enter Hungary through Serbia diverted to Croatia in search of a new route to Germany.

Despite the chaos, there were few signs that European Union leaders, or the governments of other countries along the human river of people flowing from war and poverty, were close to imposing any order or even talking seriously about harmonizing their approaches and messages to the migrants. Instead, countries continue to improvise their responses, as Croatia did Thursday, and Slovenia — the next stop along the rerouted trail — is likely to do in coming days.