& is not a valid icon name (use input help)

What causes this issue?

In the "Icon name" field, you specified either a text which the system
cannot interpret or an icon name which is not allowed for the screen
element type used.

System Response

Not all icons can be used everywhere on the screen. For example, you
can use only a restricted set of icons on pushbuttons. The system
rejects invalid or unknown icons.

How to fix this error?

By pressing F4 when on the "Icon name" field, you can get a complete
list of all icons that are allowed for the screen field type used. From
this list, you can choose an icon.

Error message extract from SAP system. Copyright SAP SE.