Enter the delimiter & at the end of the string

What causes this issue?

The character string begins with a delimiter, but does not with the
same characters. Delimiters are: / - . , : ; < > ( and ) .

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?

Choose a delimiter not in the actual character string, and close the
character string using the same delimiter, for example,
/character_string/.

Error message extract from SAP system. Copyright SAP SE.