I need to add 2 extra people to a certain task that currently has 4 resources assigned. As soon as I add one, project automatically extends the duration of the task without reason. I've tried everything I've read so far: Disabling calculations, changing task type, disabling effort driving task (both in options and in the task) and nothing works, project keeps extending the duration of this task.

I even tried changing to the original task duration manually after adding the new resources, but project doesn't reverts the task date to the old one.

Please, I really need help with this. I've had a lot of headaches working with this software but this one has me totally beaten.

  • I did not use that program for a long time, but I remember there was an option to choose from "fixed effort", "fixed duration" or "fixed something else". I guess you should choose the "fixed duration" property of the task, before adding the resources.
    – virolino
    Nov 14, 2022 at 13:58
  • "I've had a lot of headaches working with this software" - welcome to the club :). And welcome to ProjectManagement.SE
    – virolino
    Nov 14, 2022 at 14:00

1 Answer 1


The most common fix for the issue described is to set the Task Type to Fixed Duration prior to adding the new resources.

fixed duration

If this doesn't work for you, it's likely at least one of the resources you are trying to add has a calendar conflict with the task. Usually, you want the Calendar being used by the resources to be the same as the calendar being used by the project/task.

You can check what calendar is being used by the resource by looking at the Base Calendar field in the resource sheet. Example:

enter image description here

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