Thanks to macguba for the suggestion. I've removed some triggers and the error disappeared.
Now I have a few more questions about scripting:
1) I have the following units ej1, ej2…ej10 (not in a group) and a trigger executes the following line:
[ej1,ej2,ej3,ej4,ej5,ej6,ej7,ej8,ej9,ej10] Join me
The units join me, but when I order them to return to formation the order all follow ej3 or ej6 etc is issued. I've checked and all units are privates.
2) If I have we1,we2,we3…we20 as enemy units and I want to apply (enemyunit KnowsAbout me)>2
as a condition in a trigger for all of them, what is the best way of doing it instead of writing it for
each one of them.
3) The same question applies if I want to set the condition Getdammage
enemyunit >=1.