A specific project is not saving back to clarity and instead you see a 'Project save failed' error.
In the app-ca.logs, you see the following Warning message 'ImportTaskProcessor.doProcess(): Illegal Task Start and/or Finish dates' related to schedulers.postProject.
Tip: To get to the app-ca.logs, see the following KB that will walk both On Premise and SaaS customers on steps to retrieve the log: Access the app-ca.log or other Clarity Logs
This is due to their being an invalid date sequence that is not supported with Clarity. The Start date of a task must be less than or equal to the task's Finish date to be able to be saved back to Clarity. This may be noticed with a manually scheduled task. One possible cause of the invalid sequence of dates happening may be related to the task unexpectedly being converted into a milestone. To avoid tasks being changed unexpectedly into milestones, follow the recommendations in the following KB: MSP: Tasks are changing to 0 day duration / milestones
Release : All Supported
Component : Clarity Microsoft Project Interface
Check for any tasks that have a Start date later than the task's Finish date. If any are found, update the task dates so that the task's Start date is earlier than the task's Finish date.
There are a couple of options you can use to check to see if any tasks are impacted by this issue. See those options below.
For other causes of the Project Save failed error see: