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Attribute 'faction3' of 'ALiVE_mil_OPCOM' logic have misconfigured default value (Expected values are 1 or 0 which states for true or false)

--> This message says that there is miscvonfigured default value, which actually was correct some time ago (default = true) but this has been changed long since.

This is what it is now in cfgVehicles.hpp of alive_mil_opcom:

class faction3
                        {
                                displayName = "$STR_ALIVE_OPCOM_FACTION";
                                description = "$STR_ALIVE_OPCOM_FACTION_COMMENT";
                                class Values
                                {
                                		class NONE
                                        {
                                                name = "NONE";
                                                value = "NONE";
                                                default = 1;
                                        };
                                        class NATO
                                        {
                                                name = "NATO";
                                                value = "BLU_F";
                                        };
                                        class IRAN
                                        {
                                                name = "CSAT";
                                                value = "OPF_F";
                                        };
                                        class GREEKARMY
                                        {
                                                name = "AAF";
                                                value = "IND_F";
                                        };
                                        class REBELS_BLU
                                        {
                                                name = "REBELS BLU";
                                                value = "BLU_G_F";
                                        };
		                                class REBELS_OPF
                                        {
                                                name = "REBELS RED";
                                                value = "OPF_G_F";
                                        };
                                };
                        };

BTW: I can't open the mission.sqm as its binarized to check, but...

If its a mission that you copypasted from some old one it would be worth trying to replace the OPCOM modules totally and set it up freshly.