Optimizer error &1 (see SNP optimizer log data)

What causes this issue?

Error &V1& occurred when running the SNP optimizer.

System Response

Optimization-based capacity leveling uses the SNP optimizer to level
resource overloads. The optimizer error that occurred means that
capacity leveling could not be performed successfully.

How to fix this error?

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.