Agreement type &1: too many fields in the VAKEY

What causes this issue?

Too many fields have been indicated for updating the variable key for
the agreement type &V1&. The field length of the variable key (100
characters)is too short to store all data.

System Response

Not all fields are updated when the variable key is generated.

How to fix this error?

Reduce the number and/or length of the fields for updating the variable
key for the agreement type &V1&.

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.