Order could not be scheduled

What causes this issue?

An order could not be scheduled.
INCLUDE URSACHEN OBJECT DOKU ID TX
You have set the planning direction <ls>backwards</> in the strategy
profile, but there is not enough working time or capacity between now
and the requirements date for scheduling to take place.
You have not maintained a working time or a capacity for the resource.
You have made settings for an activity in the Production Process Model
so that the activity cannot be interrupted by breaks. If the activity
is longer than the working time between two breaks or between two
non-working times, the system cannot schedule the activity.
The maximum intervals between activities that you have maintained in
the Production Process Model are too short. The system cannot schedule
the order without violating these maximum intervals.
You wish to plan based on characteristics and have assigned
characteristics to operations in the order, but not to the resources
with which the operations should be processed. Because the system
cannot find any resources with suitable characteristics, it cannot
schedule the operations.
There are other possible causes.

How to fix this error?

Analyze the causes:
<zh>In the strategy profile</>
If necessary, activate the strategy profile in the planning direction
<ls>backwards with return</>.

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

<DS:TRAN./SAPAPO/CDPSC1>Call up the strategy profile immediately</>
<zh>In the resources</>
If necessary, maintain the working times and capacities for the
resources.
Check the characteristics you have assigned to the resources.
<DS:TRAN./SAPAPO/RES01>Call up resource maintenance immediately</>
<zh>In the Production Process Model</>
If necessary, configure the long activities such that they can be
interrupted by breaks.
If necessary, increase the maximum interval allowed between the
activities.
Check the characteristics you have assigned to the operations.
<DS:TRAN./SAPAPO/PLN1>Call up the Production Process Model immediately
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Error message extract from SAP system. Copyright SAP SE.