Hi Joana, how are you? I faced some similar issues, in a custom dossier, not in the X3 dossier. The solution I used is to get the name of the program when it is opened in X3, go to Development -> Windows -> Type the name of the program (which appeared on the error screen and which you cannot access) in the description field of the left- list -> Click on the Global Validation button -> Exit and enter X3 -> See if the program no longer gives the error.