Specify loop block end line without continuation lines

What causes this issue?

Subsequent lines have already been defined for the loop block.

How to fix this error?

To define a loop block, position the cursor in the first line of the
loop and press F16. To define a loop block with several lines, repeat
the above procedure for the last line of the block. Then define the
loop factor by pressing F22. If the loop factor was increased following
definition of a single-line loop and the loop block must be changed,
then delete all subsequent lines using F23.

Error message extract from SAP system. Copyright SAP SE.