I have a fairly extensive project where a lot of tasks are showing negative slack - up to 300 days!


Some are constrained, but i've interrogated it fairly extensively and I can't find the root cause. There are even tasks without successors that are showing as critical.





Is there an easy way to trouble shoot this? Really all I want it to be able to show my critical path through to project finish, but these constrained tasks distort that by making tasks that affect the finish date of a constrained task critical, as opposed to those that affect the finish date.



Project file can be found here WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free

Thanks in advance

You need to look at the number of constraints you have in the schedule. Are all of them necessary? Trace the Finish No Later Than (FNLT) constraint dates in the schedule and see impact on activities.

E.g. ID 271 has a FNLT date of 01-Sep-23 and its predecessor ID 270 also has a FNLT date of 01-Sep-23 but ID 270's predecessor, ID 247 finishes on 21-Nov-23, therefore it has a Total Slack of -304 days because of the FNLT constraint date of 01-Sep-23 on IDs 270 & 271.

Thank you, sorted! I thought I had removed those constraints as they were from a previous iteration, but had clearly missed.

I created a new filter to display all FNLT constraints and removed them that way.

Thanks again.