circular reference in linked project plan

[Riko Wichmann]

Dear all,

we are running MS Project 2007 Enterprise for a project consisting of
about 40 sub-project. Each of these sub-project has its own plan on the
server. Sub-project plans are interlinked via a general "Milestone" plan.

When opening the milestone plan, project will open all linked sub-project
plans and eventually pops up with an error message, that some task is
linked to another task with links back to the original one. However, no
indication is given on where this circular reference may occur.

Is there are best practice somewhere how to trace circular references
except of starting to delete links until the circular reference
disappears?

Thanks in advance,

Riko

 

[John]

Dear all,

we are running MS Project 2007 Enterprise for a project consisting of
about 40 sub-project. Each of these sub-project has its own plan on the
server. Sub-project plans are interlinked via a general "Milestone" plan.

When opening the milestone plan, project will open all linked sub-project
plans and eventually pops up with an error message, that some task is
linked to another task with links back to the original one. However, no
indication is given on where this circular reference may occur.

Is there are best practice somewhere how to trace circular references
except of starting to delete links until the circular reference
disappears?

Thanks in advance,

Riko

Riko,
This is a fairly common problem when interim milestone plans are
included in the mix. If the links only went to the milestones there
wouldn't be a problem but in my experience all too often the user links
successor tasks to the milestone plan and that is fertile ground for
circular references.

The most common cause of circular references are links to summary lines.
If you have that scenario, eliminate those links by replacing with links
only to and from performance tasks. The second most common cause are
"backward pass" links. You may not realize it but users can create
backward links by getting overzealous with the linking structure. Check
each subproject for cross-project links that may be going back in time.
I'd start out by opening each subproject with the option to display
external links (Tools/Options/View tab. Look for "ghost tasks" with
earlier dates than the live predecessor task.

As a final fallback, I do have a macro that converts a dynamic master
file to a static master while preserving the cross-project links. I've
found that it is a great tool for finding circular references because it
will flag an error directly on the task that has a bad link. The macro
is not freeware but if you are interested, you may contact me direct at
the address below.

John
Project MVP
jensenljatatfastmaildotdotfm
(remove obvious redundancies)

 

[Riko Wichmann]

Hi John,

thanks for your suggestions. I'll go hunting again tomorrow.

By now, I'm fairly certain, the loop should be entirely within one sub-
project plan. The reason for this is that in the milestone plan, all
links across sub-projects are decoupled: The milestone from the providing
sub-project is linked into the milestone plan. There, a copy of the
milestone is created with a constraint date and completely disconnected
from the original milestone. The receiving sub-project is then linked to
the copied milestone with the date constraint in the milestone plan.
Therefore, there is no direct connection between 2 sub-project plans.
Everything is under tight control by the maintainer of the milestone plan
(myself).

If that is true, I should just open all linked sub-projects and one of
them should pop-up with the same error message ...

Thanks for you hints,

Riko

 

[John]

Hi John,

thanks for your suggestions. I'll go hunting again tomorrow.

By now, I'm fairly certain, the loop should be entirely within one sub-
project plan. The reason for this is that in the milestone plan, all
links across sub-projects are decoupled: The milestone from the providing
sub-project is linked into the milestone plan. There, a copy of the
milestone is created with a constraint date and completely disconnected
from the original milestone. The receiving sub-project is then linked to
the copied milestone with the date constraint in the milestone plan.
Therefore, there is no direct connection between 2 sub-project plans.
Everything is under tight control by the maintainer of the milestone plan
(myself).

If that is true, I should just open all linked sub-projects and one of
them should pop-up with the same error message ...

Thanks for you hints,

Riko

Riko,
I doubt the problem is within one subproject because if that were the
case that project would flag an error when the file was opened by itself.

Maybe the "control" is a little to tight in your milestone plan. Rather
than apply constraints, it is better to let the plan "float" and keep an
eye on the Total Slack field. Manage the overall project by resolving
negative slack drivers instead of trying to force the issue with
constraints.

Good luck in your search.

John
Project MVP