Actually fixing a crack in a garage door panel can be a difficult and even impossible task.
Garage door exterior surface cracked.
If your garage door is metal or vinyl it is much more difficult and even impossible to fix.
Cracking due to poor compaction of sub grade before pouring a concrete slab it is important to prepare what is often called the subgrade which usually involves compacting the sub grade and base i e.
Loss of caulk s initial adhesion and flexibility causing painted caulk to crack and or pull away.
The bottom portion of your garage door is most susceptable to this kind of wear which can lead to water damage and wood rot.
If the garage door panels are wood then yes a garage door panel that is cracked could be fixed using wood fillers and glue.
Caulk paint cracking or crawling the cracking of the paint film over a caulked area.
Wooden door patch repair an old wooden garage door made of fiber board wood or other composite wood materials can become warp and receive water damage from years of rain and snow splashing and pelting its surface.
Repairing the doors requires a little work and depending on how large the crack is could be.