I have detailed in a dedicated article the process for making a sweet pastry dough, but today, I decided to go through the different problems you may encounter and the main questions that apprentice bakers ask!
What type of flour for a sweet pastry dough?
For tart dough, especially when you're starting out, it's best to use a flour with less gluten. This helps limit the risk of the dough retracting during baking. Therefore, T55 flour is ideal for making sweet pastry dough.

Sweet pastry dough that retracts
A dough that retracts is the main problem when making a tart. This is due to gluten development in the dough during kneading. Gluten is necessary for the elements to amalgamate, but too much of it causes the dough to retract after baking, limiting the height of the edges. To avoid this, you can use T55 flour, which has less gluten than T45 flour. Also, to limit gluten network development, it's important not to overwork the dough once the flour is hydrated.
Another technique: make sure to let the dough rest in the refrigerator both when it's kneaded and again after the tart pan or ring is lined with the dough. These three techniques will help you avoid a sweet pastry dough that retracts during baking.
Sweet pastry dough that flakes
A dough that flakes is due to a lack of gluten. Just as too much gluten can cause problems during baking, a dough lacking in gluten will flake. You need to find the right balance by kneading the dough until it's homogeneous but stopping once it reaches this state. To prevent the dough from retracting during baking, make sure to let it rest in the refrigerator before rolling it out and before putting the tart in the oven.
Sweet pastry dough that breaks
A dough that breaks is a result of a high proportion of butter. It's difficult to work with but also what makes the richness of the dough. You can add a little almond flour to the dough to make it less breakable. But the real trick to avoid breaking, is not to roll out the dough too cold. Let it rest first.
Sweet pastry dough that sticks
If your sweet pastry dough is sticking, it's because it's too warm. You need to put it in the refrigerator for a few minutes to cool down. Don't forget also to flour the work surface well: this means putting a little flour on it to prevent the sweet pastry dough from sticking.
Sweet pastry dough that sags or falls
A sweet pastry dough that sags is due to two things: a too-worked dough that has developed too much gluten (refer back to the section "sweet pastry dough that retracts") and improper tarte lining. When you line a tart pan, you should press your thumb against the edges of the ring to flatten the dough on the sides. During baking, it will adhere correctly to the ring and shouldn't sag or fall.

