Differences between Project XML and MPP files

Copper Contributor

I am using Project Standard 2016 (Version 1908 Build 11929.20300)


I have experienced an issue where I am getting differences in data between an original *.mpp file, and an *.xml that I exported from that mpp file. The differences then continue to occur if I then save the first XML file as an XML file again.


I have attached the 3 Project files in the .Zip file.


These are my steps:

  1. Opened the "Sample.MPP", and took a screenshot of the first 23 tasks
  2. Saved the file as "Sample.XML".
  3. Opened that "Sample.XML" file, selecting 'Import as New Project' when prompted. Took a screenshot of the same Tasks.
  4. Saved that as a second XML file "Sample_2".XML (no changes were made to it).
  5. Opened that "Sample_2".XML file, selecting 'Import as New Project' when prompted. Took a screenshot of the same Tasks.

I compared the screenshots between all 3 files, and noticed that Dates and Durations were continuously changing from the original MPP file (see attached file Differences.png)


I checked the Calendar Options and Working Time settings after each file is opened, and they seem all the same: https://www.screencast.com/t/7RdF3B0BdW

I also check what the Calendar Options were for 'New Projects' and they were slightly different: https://www.screencast.com/t/3DOPdG9y


What is causing these differences?


  1. Does the XML Export have certain limitations / not support certain settings?
  2. Is there something else that is adjusting the dates when the XML file is being opened/imported as a new Project?



  • I also tested in MS Project 2019, and the issue still happens.
  • I think it may be related to the fact that the project is using the '24 Hour' calendar. I had another 2 Project files which were exporting / loading XMLs fine, but as soon as i changed the calendar in the MPP files to use "24 Hour", and then exported the XML, once that XML was opened in Project again, the dates/times changed.
2 Replies

@Estate_Master -- I am not surprised at all by the fact that you see differences between the original project and a new project created from the exported XML file.  Based on my personal experience, the XML file does not capture the timephasing of task Work and Cost values on tasks.  And I suspect your use of the 24 Hour calendar is at least partially the source of the errors.


For me, the Save to XML option is a last resort to try to fix a corrupted project.  I know that using this feature will capture the "guts" of the project, but not the exact duplicate project.  Out of curiosity, why are you using the Save to XML feature?


Please let us know and we will try to help you.


Hi @Dale Howard 


I am exporting to XML, because we are developing a C# app that uses a .Net Gantt control. That control allows users to import MS Project XML files, not MPP format.