Field &1, data element &2 with length problem

What causes this issue?

Data element '&v2&' is assigned to field '&v1&'. External length '&v4&'
was assigned to this field when the segment was saved. This either
occurred automatically by calculation of the export length of the data
element or by explicit assignment of a greater export length within
segment maintenance.
However, field '&v1&' is defined smaller in the repository structure,
namely with '&v3&' character places.

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?

Using the change times, check whether there are any inconsistent
changes and change the segment in accordance with your requirements in
the segment editor and save again.

Error message extract from SAP system. Copyright SAP SE.