Element & cannot be read with structure &

What causes this issue?

Element &v1& is in the container as a character string.
Structure &v2& is for reading element &V1& (via binding definition or
setting parameters of expression evaluation). But, structure &v2& is
not purely character string-based (does not contain only fields of the
internal types CNDT). Therefore, element &v1& cannot be read with
structure &v2&.

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.