Lower limit for unplanned characteristics should not be changed

What causes this issue?

You are trying to change the lower limit of the number range for
unplanned characteristics.

System Response

How to fix this error?

When you change the number range for unplanned characteristics, you
must ensure that,
the number of an inspection characteristic in an inspection plan does
not fall within the range of numbers for unplanned characteristics
the number of an unplanned characteristic that has already been created
does not fall within the range of numbers for unplanned characteristics
If you ignore these two rules, inspection plans and analyses will be
inconsistent.

Error message extract from SAP system. Copyright SAP SE.