Forgetting to dimple the dough
Sticking your oily fingers into the squishy dough is not only entertaining, but it also serves an important function for the focaccia. Some reports point out that dimpling the dough before baking prevents it from bubbling and burning, much like a pizza crust. If you bake your dough without dimples, the dough will collapse when the bubbles burst, resulting in sad focaccia and a sad baker.
To dimple the dough, lightly oil your fingers or the end of a wooden spoon handle and gently poke it. You don't have to follow a pattern, but try not to crush your fingers all the way to the bottom of the pan to break the dough apart. Another advantage of dimpling your dough, according to Thyme and Envy, is that you will increase the surface area when applying the final coat of olive oil. As a result, dimpled focaccia will have a much better and more consistent color.