What causes this issue?

In the analysis of the current display variants for the row types used
in the lists, the system has determined that for at least one row type,
the overall width of the fields specified in the display variants
exceeds the maximum width of the list (255).
Where this is the case, fields that cannot be displayed within the
maximum width will be cut off.

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?

To establish in which row type the maximum width of 255 has been
exceeded, go to the dialog box for configuring the individual row
types. The current setting for the width of the row is given here.
However, you should roughly double the specified number for header and
total rows, since in these rows the field descriptions are also
displayed.
You have the option of configuring the row in question so that the
fields that are cut off are displayed in a second or third row.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.