Battery Life

• Having a fully charged TomTom during an update process is crucial. If your TomTom's battery is not full during an update, this can cause the update to be faulty and incomplete, nullifying any use until the update is complete.
  
  

Weak Connection

• Having a bad connection, or losing a signal entirely, during an update results in incomplete files which will cause your TomTom to not function correctly after an update.
  
  

Corrupted Update Data

• Errors can occur when updating any type of software. It's possible some update data transmitted to your TomTom via satellite was corrupted from the source.