Check the text entered

What causes this issue?

The text starts with the character "+". The last text entered can be
transferred with the entries "+" or "++".

System Response

A warning message is displayed as there may be an input error. The text
entered does start with "+", but it is not of the form "+ " or "++
".

How to fix this error?

If the text entered is correct, confirm that by pressing ENTER. If you
want to start the copy function, correct your entry to "+". If you want
to have a control display, change it to "++".

Error message extract from SAP system. Copyright SAP SE.