How To Fix 28117 - Restriction not possible: expression not linear

SAP Error Message - Details

• Message type: E = Error

• Message class: 28 - Configuration

• Message number: 117

• Message text: Restriction not possible: expression not linear

What causes this issue?

You can only use formulas to restrict a numeric characteristic if the
formula in the characteristic you want to restrict is linear.

System Response

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

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message 28117 - Restriction not possible: expression not linear ?

  The SAP error message 28117, "Restriction not possible: expression not linear," typically occurs in the context of SAP's optimization tools, such as SAP APO (Advanced Planning and Optimization) or SAP IBP (Integrated Business Planning). This error indicates that the system encountered a non-linear expression when it expected a linear one, which is necessary for certain types of optimization problems.
  Cause:
  
  Non-linear Expressions: The most common cause of this error is the presence of non-linear mathematical expressions in the model. This can happen if you are trying to apply restrictions or constraints that involve products, powers, or other non-linear operations.
  Incorrect Model Setup: If the model is not set up correctly, such as using variables or parameters that are not compatible with linear programming, this error can occur.
  Data Issues: Sometimes, the data being used in the model may lead to non-linear relationships, especially if there are multiplicative factors or ratios involved.
  
  Solution:
  
  Review Expressions: Check the expressions used in your constraints and ensure they are linear. Linear expressions typically involve only addition, subtraction, and multiplication by constants.
  Modify Constraints: If you find non-linear expressions, consider reformulating them into linear constraints. This may involve linearizing the problem or using piecewise linear approximations if necessary.
  Check Model Configuration: Ensure that the model is configured correctly for linear optimization. This includes verifying that all variables and parameters are defined appropriately.
  Consult Documentation: Refer to SAP documentation or help resources for guidance on formulating linear constraints and understanding the limitations of the optimization tools you are using.
  Testing: After making changes, test the model again to see if the error persists. It may be helpful to simplify the model temporarily to isolate the issue.
  
  Related Information:
  
  Linear Programming: Understanding the principles of linear programming can help in formulating the correct constraints and objectives.
  SAP Notes: Check SAP Notes and Knowledge Base Articles for any specific patches or updates related to this error.
  Community Forums: Engage with SAP community forums or user groups where similar issues may have been discussed, and solutions shared.
  Training and Resources: Consider training on SAP optimization tools to better understand how to set up models and constraints effectively.
  
  By addressing the non-linear expressions and ensuring that all constraints are linear, you should be able to resolve the error message 28117 in SAP.