Project Plan 365 will alert you when you set the following incorrect task dependencies cases:

• Circular dependency – when tasks are already liked together;
• Task chain dependency – when tasks are already linked through another task chain;
• Dependency to the task itself – when making a task a predecessor of itself;
• Dependency between a summary task and a subtask – when linking a summary task to one of its subtasks;
• Linking predecessor task twice to the same successor;
• Adding invalid predecessor value;
• SF and FF dependency for a summary task;
• Linking non-existent tasks;
• Adding invalid lead/lag time value.