ArmA common errors in configs which you should and need to avoid at all cost.

For example on many many addons (even in BIS material) you'll see this arma.rpt error:

Updating base class ->MGunCore, by ca\weapons\config.bin/cfgWeapons/MGun/

You can avoid this error by not changing the MGun class, instead using your own new class by inheriting from this MGun directly.

These are few examples how its done.

Bad config:

	class MGunCore;
	class MGun: MGunCore
	{
		displayName = "MyCoolGun";
	};

Good config:

	class MGun;
	class TAG_MGun: MGun
	{
		displayName = "MyCoolGun";
	};

Other common errors:

Updating base class ->Default, by ca\anims\characters\config.bin/CfgMovesBasic/DefaultDie/
Updating base class ->Default, by ca\anims\characters\config.bin/CfgMovesMaleSdr/States/Crew/
Updating base class CannonCore->Default, by <addon>\config.bin/CfgWeapons/Cannon30/
Updating base class CAWorld->TAG_baseWorld, by <addon>\config.bin/CfgWorlds/Intro/
Updating base class Civilian->SoldierWB, by <addon>\config.bin/CfgVehicles/SoldierWCaptive/
Updating base class controls->, by <addon>\config.bin/RscDisplayArcadeMap/controls/
Updating base class controls->, by <addon>\config.bin/RscDisplayLoading/Variants/Loading_East1/controls/
Updating base class DefaultClutter->, by <addon>\config.bin/CfgWorlds/Intro/clutter/GrassGeneral/
Updating base class Face1->, by <addon>\config.bin/CfgFaces/Man/Face10/
Updating base class HeavyReammoBox->Land_garaz_s_tankem, by <addon>\config.bin/CfgVehicles/HeavyReammoBoxEast/

All can be avoided by not touching these base classes, just inheriting from them into your own new classes.