Copy or Cut&Paste could not be executed

What causes this issue?

Copy or Cut&Paste could not be performed. This is due to one of the
following:
At least one cell in the target area is read-only. Fixed cells are also
read-only cells
The target area is smaller than the source area

System Response

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

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.