&1 &2 > &3 &4: Conflict due to moved date

What causes this issue?

You have defined a constraint for the project element <(>&<)>V2& (
<(>&<)>V1&). However, this constraint shifts the project element
<(>&<)>V4& (<(>&<)>V3&) on the time line so that it overlaps
with a predecessor or successor or is before the fixed start date or
fixed finish date of the project.
<ZU>Example:</>
Two phases P1 and P2 are linked by a relationship with a <ZH>positive</>
lag. You set the <ZK>Must start on</> constraint for a task that belongs
to phase P2 and the constraint date is before the finish date of phase
P1. This causes an overlap between the phases P1 and P2.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

System Response

The system resolves this scheduling conflict by resetting the constraint
dates for the project element <(>&<)>V2& (<(>&<)>V1&).

How to fix this error?

Check the relationships for the project element <(>&<)>V4& (
<(>&<)>V3&). Adjust the relationships accordingly. If you want the
project elements to overlap, define relationships with a <ZH>negative</>
lag.
The project element <(>&<)>V4& (<(>&<)>V3&) is a phase:
Do not allow phases to overlap; the phase concept works on the basis
that phases are disjoint.
The project element <(>&<)>V4& (<(>&<)>V3&) is the project
definition:
Set the constraints on the project element <(>&<)>V4& (<(>&<)>V3
&) accordingly or adjust the constraints on the project
definition.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.