ALV error: overwritten protected field

This problem was accidentally encountered during the recent ALV development:

 

Data can be output normally, but when I back or double-click the row, the short dump is generated. The error message is:

 

Error at assignment: overwritten protected field.

 

 

The error message is:ProgramTries to overwrite protected fields during execution.

 

After repeated checks, it is found that box_fieldname is set in layout, and the field corresponding to the set value does not exist in the internal table.

Then, just comment out this statement!