Not baking for long enough
The baking time on most banana bread recipes surprises many people. How could something baked in such a small pan take so long? Remember that banana bread is a dense batter that takes a long time to fully bake in those deep bread pans. If your banana bread is still raw in the middle, the most likely cause is that you removed it from the oven too soon. Most loaves will bake for at least 50 minutes.
The crust should be golden brown, but appearances can be deceiving. Here are some pointers to ensure that your loaf is evenly baked. If you gently press your finger into the top of the loaf and it leaves a dent, it needs to be baked for another 5 minutes. Insert a toothpick into the center of the bread as well. It has baked long enough if it comes out clean.