Task cannot be completed in the time allocated because there is a scheduling conflict between this task and another one to ...

Task cannot be completed in the time allocated because there is a scheduling conflict between this task and another one to which it is linked. Try the following: Change the type of constraint on the successor tasks to As Soon As Possible or some other constraint that doesnt fix it to a specific date. Remove the link between the conflicting tasks.  Shorten the duration of one of the tasks.  Change the start and finish dates of one of the tasks. If the task to which the other task is linked is not constrained and it is a summary task, check the constraints on the subtasks.