How To Fix CM121 - Reallocation to the referenced operation & is not possible.

CM121 - Overview

• Message type: E = Error

• Message class: CM - Task list messages: Material component allocations

• Message number: 121

• Message text: Reallocation to the referenced operation & is not possible.

What causes this issue?

The material component you want to reallocate is allocated to an
operation which is referenced from an operation set. Material
components that are allocted to referenced operations cannot be changed
in the routing containing the reference.

How to fix this error?

If you want to reallocate the material component, you can do this by
maintaining the reference operation set. Note, however, that the
change is valid for all routings containing a reference to the
operation set.

Error message extract from SAP system. Copyright SAP SE.

CM121 - Details

• The SAP error message CM121 ("Reallocation to the referenced operation & is not possible") typically occurs in the context of production planning and control, particularly when dealing with capacity planning and scheduling in SAP. This error indicates that there is an issue with reallocating resources or operations in a production order or a related process.
  Causes of CM121 Error
  
  
  Capacity Constraints: The operation you are trying to reallocate may exceed the available capacity of the work center or resource. This can happen if the work center is already overloaded with other operations.
  
  
  Status of the Operation: The operation you are trying to reallocate may be in a status that does not allow for reallocation (e.g., it may be completed, closed, or in a different phase).
  
  
  Dependencies and Sequencing: There may be dependencies between operations that prevent the reallocation. For example, if the operation is dependent on the completion of a previous operation, it cannot