Contents of temp. storage are inappropriate (unable to insert)

What causes this issue?

You have one of the following two cases:
You are editing the elements of a tabstrip control, chose the "Paste"
function containing temporary storage but the cursor points to an
element whose type does not suit the element list.
You chose the "Paste" function when editing the columns of a table
control and the cursor points to the field "Field name of the line
selection column" or the field "Title for table column".
Exactly one field can be placed in this cursor position.
The temporary storage from which you want to paste contains more than
one element or the element type does not agree with the attributes of a
line selection column.
Only fields that can be converted to checkboxes, such as input/output
fields of length 1, can be used as line selection columns.

System Response

The system cannot perform the paste.

How to fix this error?

If you want to place a field as line selection element or as title,
only select a single field with a valid type to be copied from the ABAP
Dictionary or program.
If you want to copy pairs consisting of input/output field (template)
and text field (keyword) as new columns of the table control from the
ABAP Dictionary, position the cursor on the element for the table
column where you want to paste.

Error message extract from SAP system. Copyright SAP SE.