Although you feel great cutting a blueberry pie sometimes things don’t go that way. You may find blueberry pie filling turns out runny. There are some factors behind this messy situation. Such as- 1. If the pie has not been baked properly for as long as is required, you may face this problem as the blueberries have high water content. In that case, you may place the pie into the oven again for some more time. 2. If the crust wasn’t cooled properly before adding the filling, the pie may turn runny. 3. Sometimes you might ignore some essential ingredients such as cornstarch, tapioca flour, gelatine powder, etc. to thicken the pie and that can make the thing messy for you. This unwanted situation may teach you that, next time you should be more careful about it while preparing a blueberry pie.