Text field contains invalid characters

What causes this issue?

You are trying to enter a prefix or a suffix and have enclosed your
entry in inverted commas in order to be able to display extra spaces
(blanks) following the entry. (Inverted commas that occur within a text
are not automatically doubled when displayed).

System Response

The symbol can only be included in your text once you have corrected
this error.

How to fix this error?

Normally, SAPscript encloses all text entries of this type in inverted
commas for you. Whenever it does this, however, no extra spaces
(blanks) can be displayed at the end of your text. If you want to
display blanks at the end of your text, you must insert inverted commas
preceding the text yourself. You must double all inverted commas that
you insert into the body of your text.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Examples using a prefix:
,,Your entry,,,,Result
,,abcde,,,,,,&'abcde'...
,,'abcde,,,,,,&'''abcde'...
,,'abcde ',,,,&'abcde '...
,,'abc''de ',,,,&'abc''de '...
,,'abc'de ',,,,-> error message

Error message extract from SAP system. Copyright SAP SE.