Project 2013 vs Project 2016 Critical Path RRS feed

  • Question

  • Hi,

    While working on a project with a colleague, we discovered that Critical Path is not calculated the same in Project 2013 and Project 2016.

    We created a small project to illustrate the difference. We made the exact same steps in both versions and we got different results. Also, if we open in Project 2016 the file created in Project 2013, after using the "Calculate Project" button, the Critical Path changes. We read the documentation and we found that Critical Path is calculated based on Late Start and Late Finish and we saw that these fields are different in two versions.

    I attached an image comparing the two projects (

    Does anyone know why this is happening?


    Wednesday, October 25, 2017 10:03 AM

All replies

  • It hard to say what is happening because you have mix between manual and schedule task.  It may  be the order that tasks were entered and dates that have been entered.   Manual  tasks are not part the schedule engine and ignore.

    For example, looking at the late finish date of T1,  some kind of slight of hand or movement of task or switching between manual and schedule, came up with November 7.

    To really answer question, each and every step in creating the schedule would have to be provided.  There are over 500 fields in the task row and did any of these get edited as well?  We only see what you provided in screen shot.

    Michael Wharton, MVP, MBA, PMP, MCT, MCTS, MCSD, MCSE+I, MCDBA
    Blog contains my field notes and SQL queries

    Wednesday, October 25, 2017 10:23 AM
  • Hi,

    Here are the steps to reproduce the difference:

    1. File -> New Project (with new tasks: manually scheduled)

    2. Add task t1, set duration to 5 days, set start date to 25 October 2017

    3. Add task t2, set task mode to auto

    4. Add task t3, set duration to 1 day, set start date to 31 October 2017

    5. Indent task 2 and task 3 (make task t1 summary over t2 and t3)

    6. Add task t4, set task mode to auto

    7. Outdent task t4

    8. Set duration of task t4 to 10 days

    After I set the duration of task t4 to 10 days (step 8), the critical path is not calculated the same in Project 2013 and Project 2016. In Project 2013, task t3 and task t4 are critical and in Project 2016, task t3 isn't critical and task t4 is critical.


    Wednesday, October 25, 2017 10:58 AM
  • Alin,

    This exercise has no real-world application.

    Calculating a critical path with manual tasks is ridiculous.  Calculating a critical path with no relationships is ridiculous.  Just like many features in Project, the fact that something is ridiculous doesn't make it impossible.  Project executes the forward and backward passes and calculates early and late dates for all tasks - including manual tasks. In the absence of any deadlines, constraints, successor relationships, or resource leveling, the only rational late finish for any of the tasks is 7Nov'17 - the end date of the project.  That's the way MSP 2010 (and apparently MSP 2016) calculates it.  If someone else can confirm that MSP 2013 calculates differently, then I would suspect that the algorithm for handling CPM calculations through manual summary tasks - which is essentially meaningless and arbitrary - has evolved for the 1 person in a thousand who cares about it.

    Wednesday, October 25, 2017 2:04 PM
  • Hi,

    Thanks for the response! I know that this isn't a realistic scenario, but I tried to illustrate the difference. We have multiple large mpp files and if we open them in MSP 2016 and press calculate project, multiple fields are changed (including start and finish of a task). 

    I tried to create the same scenario in MSP 2010 and I got the same results like in MSP 2013 (

    Is there any list with this kind of changes in MSP 2016 (regarding to scheduling/critical path engine)? I would like to know how compatible MSP 2013 and MSP 2016 are, or what modifications should we make in order to have no differences between the data in the two versions.


    Wednesday, October 25, 2017 2:37 PM
  • Alin,

    It seems you and I are getting completely different results from this simple exercise in MSP 2010.  That makes me wonder about your software installations.

    First thing to check: is your system fully patched/updated.  Your Project 2010 version/build should be 14.0.7176.5000.  Is it?  You may need to run Windows update to make sure that all the Project installations (including 2013 and 2016) are fully updated.

    Wednesday, October 25, 2017 4:03 PM
  • Hi,

    Thanks for the suggestion Tom! After I updated the MSP 2010 to the latest version, the critical path is like in MSP 2016.

    I updated MSP 2013 to the latest version (15.0.4971.1000) and the critical path algorithm still works differently (like it was before).

    Now I have MSP 2010 and MSP 2016 behaving the same, and MSP 2013 behaving differently for critical paths.

    Thursday, October 26, 2017 6:00 AM
  • Alin,

    As noted earlier, your example implies an evolution of the handling of manual summary tasks from 2010 to 2016.  I doubt if this is documented anywhere, as both hierarchical/summary logic and manual tasks are pretty much proprietary to MSP.

    Your penultimate post indicates that re-scheduling your real-world projects (i.e. hitting F9) after opening them in MSP 2016 caused significant changes to dates.  Since this implies that auto-calculation is normally off, I'd first confirm that they were scheduled/calculated before saving in MSP 2013.  Could be as simple as that for some things.

    Sorry I can't help more - both MSP 2013 and MSP 2016 seem to be essentially downgrades (from MSP 2010) for the standalone user, so I've avoided them.

    Good luck, tom.


    Thursday, October 26, 2017 2:07 PM